Okay, two points. First, even having different primary spellcasters use different spell levels would make the various spellcasting systems much more difficult to present. Rather than having one chart for how many Vancian memorized spells per day a spellcaster gets at each level, you'd need a different chart for classes with 5, 7, and 9 levels of spells. (Same for distribution of spell points, etc.)
As long as the power structure is along the lines of .. wizard has more spells known, less per day .. sorcerer has more power per day (or in a single go) but less spells known .. and the warlock has a small list but infinite uses - or the equivilent - what does it matter which system. There COULD BE a default set in the classes chapter of the book, then at the back or even under the magic section they talk about variants or ways to change that default. That way new players wouldn't be lost but experienced players could use whichever mechanics they like right out of the core.
Second, having five or seven levels of spells wouldn't actually change the basic conceits of wizard-style spells: spells must have a static power level tied to their level. In 5e, the Fireball spell does the same damage whether you cast it at level 5 or at level 20. By forcing every spellcasting class to fit this mold (in the name of "modularity"), you're actually closing off the very common archetype of a spellcaster who uses a limited number of spells but gets more powerful with them as he/she progresses. The warlock works this way in the playtest and in 3.5e: you're casting Eldritch Blast at level 1 and at level 20, but it gets much more powerful.
The example really isn't important anymore so I'll drop it. But I think all of this has to do with the nature of spells, certainly if you are casting the same spell at 20th then it should look different from level 1. If you have a default style or table and then a way to EASILY modify that mechanic into something else then it is a win-win. That way they could make all casters use the 3e/spell slot system and give options to turn it all into AEDU.
IMHO that mode fo thinking leads to the PHB as a Rules Compendium: here is a list of cool mechanics we thought up, mix and match them to make your preferred character. Now we "advanced" players tend to enjoy stuff like that - I personally love homebrewing - but there's a lot to be said for having The Pros design classes all the way through and make them as seamless and elegant as possible.
I think it should certainly be simple. But let me put it this way. (You need to be familiar with 3e's regular spells and psionics.) If, in the spells chapter, they had the spell listed with its original 3e style involving spell level, and then another minor section - maybe 2 lines or something - that gave its psionic (pp) cost what would be the harm? Two birds with one stone and you are looking at an extra 2 lines per spell. It would have a similar effect but with small adjustments to allow completely different spell mechanics all the while being in the same book. Now there would be no need for PHB and Expanded Psioncs Handbook, we would only need one.
Sorcerers and warlocks only came into existence as 3.x alternates to prepared Vancian spellcasting.
I never really played any edition prior to 3e so I'll have to take your word for it. Although, here I assume you are using vancian as in memorization, because both of those classes still used spell slots.
I'm sorry - do you mean here that memorization should or shouldn't be required for the wizard class? My assumption from the L&L article was that non-preparation would be an option as well.
In my ideal world, the default wizard (which would be known as the universal wizard) would use a spellbook and memorization. But I would also have several different kinds of wizards put under the same heading. For me wizards are less about spellbooks and memorization and more about contingencies, preparedness and versatility. As well as power sources drawn from the ether and not from their own blood. All of these qualities would work with a blood mage, a wild mage, a psion, and so on.
And for me a sorcerer would be about power from within, be that a bloodline or something else. I think sorcerers should have less spells known or available to them because they aren't about that. But they should instead have a greater impact or explosion of power above the wizard. Granted this is mostly foreign to 3e's style so I don't know where I got it but that is my preference.
To be clearer, in the current playtest the sorcerer automatically grows scales and gains an elemental resistance when he has used 10 willpower (spell points). This specific effect - automatically transform the sorcerer when he's used a chunk of his magical power for the day - would be tough to translate to a spontaneous Vancian system. (Does it trigger when he casts his first level 3 spell of the day? When he casts all his level 2 spells?)
Maybe they would get something like a barbarian's rage (again from 3e) and a certain amount of rounds they would grow scales and get other effects. Although this growing scales thing IS fairly 5e dependent and not so universal so I don't know if that is even necessary.
However if it is necessary and a part of sorcerers then I absolutely expect them to make concessions for it no matter which mechanics the DM/setting associates with sorcerers. For all I care sorcerers could be set to spell-slots, with warlocks having power points and wizards having at wills. The powers themselves (effects and oomph) have more to do which the class's uniqueness than the mechanical structure.
They already tried this in the abstract a while back with L&L columns on class concepts. We got lots of stuff like "the fighter is good at fighting" and "the paladin hates evii," which IMHO doesn't get you very far WITHOUT some specific mechanics to tie it to. That's the thing: the mechanical execution is closely tied to the feel of the class.
And if I were writing an L+L for my system then you would get tidbits of information. What is your point? I am not a professional developer nor am I working for WotC. I give them (and you) feedback but I don't do their job for them, especially when I'm working on my own system.
To take a 4e example: if I asked you what the fighter is, you wouldn't say, "He's a guy who marks his enemies so he gets free attacks on them if they attack someone else." But in thinking through the martial defender concept and how it would play out, they came up with marking mechanics - which I believe are actually quite good at making the player "feel" like a defender.
Actually, I would define 4e's fighter as a guy who marks. And if I didn't then I would certainly be forced to define him as a melee fighter and nothing else. I don't see what this has to do with the mechanics the fighter is using - BAB, AEDU. It has to do with his powers, just as casters would and should be.
Spellcasting mechanics seem the same to me. Want the wizard to be a nerdy guy who gets incredible power through careful study and preparation? Make preparation a key part of playing the class effectively. Want the warlock to be a guy who makes a deal to borrow magical power but at a deep personal cost? Well, he's not going to need to study like the wizard, and he's not going to drain all his energy in casting - after all, the whole point is that his magic is supposed to come "easy!" Give him encounter powers instead but make him stay in close magical contact with his patron. The mechanics reinforce the archetype and spur the player to approach situations like his character would.
Okay I think this is the main crux of my argument. I HOPE that WotC puts more effort into one of two things.
Either (A) they can put effort into allowing me to make whatever kind of caster I want. That means mixing all toolkits I can until I get the desired outcome. That means allowing me to play a guy with a breadth of options and any system I prefer and calling that class a wizard. Instead of having to take a 'sorcerer' and call him a wizard so that I can get the sorcerer's mechanic along with all that comes with it.
What if I don't want to play a bookish prepared guy, but don't want scales or having to make a dark pact to get power? Why are those the only options.
Hopefully with this idea I can also make a fighter-wizard or even sorcerer-wizard if I wanted. The ideas wouldn't be exclusive anymore. I could combine the wizard's progression with the sorcerer's progression and not be stuck with 2 different mechanical systems.
Or (B) they make a huge whack of character classes until I can select what I want without having to get a bunch of stuff I don't and without having to give up the concept. That means making a wizard, a wild mage, a wu jen, a warlock, an illusionist, a sorcerer, a transmuter, a summoner, a necromancer, a blood mage, a truenamer, a binder, etc. Basically until they have EVERY caster from every DnD edition to date.
That way I get the options I need to make the character I want. Because in this system, which you seem to be advocating, I can swap nothing out nor get the mechanics to line up differently.
Also, don't get me started on divine classes, or ones that cross-over.
Oh, the other problem with this is that I HATE the current fluff with the warlock. So even if it had my absolute favourite spell mechanics I would avoid it.
Meh, don't like. The defining characteristic of wizards, sorcerers, psions, and so on is their casting mechanic. A wizard who casts like a sorcerer is a sorcerer with slightly altered fluff. I also think that mechanics should support the fluff, which is lost in this approach.
Everything else I wanted to say here was already covered. I just wanted to add: I absolutely agree that the classes should match the fluff and so should their powers. But I don't see anything inherently wrong with mixing AEDU or vancian or power points or w/e between the classes. A 4e wizard feels like a 4e wizard, a 3e wizard feels like a 3e wizard. I want it so that I can take the 3e mechanics or the 4e mechanics and use them with a wizard and still feel like a wizard. I'm not suggesting, I don't think anyone has been, that we take the sorcerer mechanics, abilities and spells and call them a wizard.
Honestly I'd call that bad DMing period, no matter what Chris Perkins says. I would no longer be immersed in the story and the surrounds if a DM pulled that over us. Its the dreaded badwrongfun, at least to me and my group it would be.
I really don't want to get into that conversation again, but immersion is highly subjective. And immersion is going to break for me as soon as there is non-magical healing in any form - so 4e in any form
So fire not targeting a door because it isn't a creature isn't much more of a stretch.
I'm pretty sure that's partially contradicted by rules in the DMG, where use of powers against objects is allowed at the GMs discretion. And I'm fairly sure the last part is meant for the situation where someone wants to smash a stone door with their fire spells, rather than setting something dry on fire with them. (I assume it was a dry bush, not a soaking wet one.) Alternatively, use Prestidigitation and warm something up until it catches fire.
Edit: Also, 3e made it specific that Fireball ddn't set things on fire.
Fireball :: d20srd.org
"The fireball sets fire to combustibles and damages objects in the area."
Yes it does?
Not from the designer's perspective, I don't think. It has a lot to do with how the the rules are presented. There is a sizable desire out there for a solid set of rules. Its one thing to tinker with the rules, and its another to have those options embedded in the rules. Not everyone is looking for a loose framework of malleable rules. Some people are looking for gospel-- and i think that's fair, people are dropping 150+ on books, give them a "GAME", not a "suggestion". People have limited free time, and testing out a ton of "house rules" is time consuming both in conception and testing, they just want to get out there an play! By building that modularity into the "gospel" they've enabled both types of players. They're opening doors without closing any, and that's a great thing.
The new mentality of "gospel" doesn't negate the "old school" malleable interpretation of of the game.
Also, everything we've seen so far from the design team has been moving towards a flavorful and "unique" play experience from each class. I have no doubt they're keeping this mentality, like I've said in a previous post-- they've only closed one avenue of specialization (and they're not closing it completely).
Also, the whole "does vancian define the essence of a DND wizard", they did fine in 4th without vancian, I don't see how you can argue its "fluff gospel".
As I said earlier, how hard is it so present a default setting for a class. Say how 5e is now. And then add a PART (it wouldn't even require a full chapter) to the magic, spells or another chapter about how you could use AEDU instead of the wizard's spells per day.