Well, let's see here. The fighter is at least 17th level (that's when you get two Action Surges), so we'll assume a mage of the same level. Such a mage has one spell at each level between 6 and 9, plus two spells at level 5, three each of 4, 3, and 2, and four at level 1. As a specialized blaster, the mage will of course follow the School of Evocation. And since I gave the fighter a very rare magic weapon, I'll give the mage a very rare ring of wizardry, adding one spell slot per level from levels 1 to 4.
OK - does that mean he has access to that number of spells which he may choose between in an encounter, or that he can cast a sum total of 19 spells per day? As I said, I'm not sure how 5e spellcasting is structured. Having used his L8 spell in your example, does he have to use L6/7/9 in the next battle? Other than that, seems a fair comparison.
Assume the mage is rationing spells to fight four major combats per day, and using fireball heightened as appropriate. Then a pretty typical combat, versus four targets saving 25% of the time, would be something like this:
Round 1: 8th-level fireball (11d6+5): 152.25 damage.
Round 2: 4th-level fireball (7d6+5): 103.25 damage.
Round 3: 3rd-level fireball (6d6+5): 91 damage.
Round 4: 3rd-level fireball (6d6+5): 91 damage.
Round 5: What? We're still fighting?
Again, that 25% save probability has a lot of impact on the results.
This is where my limited experience at high levels prevents me from giving a definitive answer, but I can say it's quite conservative at the mid-levels (6-7). I have often fried much larger groups than that. And evokers at level 16+ can ignore resistance.
It depends very much on what you're trying to save against, what your ability scores are, and what class abilities you've got. For that matter, the same applies to the monsters.
Your damage figures will drop off as the save percentage gets higher. The Fighter hits 90% of the time, so it does not seem unreasonable the wizard gets his spell through 75% of the time - but that should be consistent with fighting "PC equivalents". Your comments indicate 25% save success is for opponents at the bottom end of the "save pool".
A 17th-level mage, assuming maxed-out Intelligence (a safe assumption by that level), is going to have a save DC of 18. So, a foe with Dexterity 14 and no other applicable abilities will have a 25% chance to save against that mage's blasting spells. That goes for PCs too. On the other hand, many PCs have special abilities that improve their saves. For instance, a 13th-level fighter gets to roll all saving throws twice and take the best result.
But a typical opponent for L17 characters will roll 1d20 + 2 and hope for the best? Seems like my Save or Suck spells are pretty effective then. In the same four rounds you hypothesize me casting four fireballs, I can cast four "save or lose" spells that target a single opponent, and expect that three of them are done for, leaving one for the rest of the party to deal with. That seems not to compare favourably with Blasting, especially if my specialty abilities enhance those save or sucks as much as the evoker's appear to enhance blasting.
It hits up to six creatures. Those that fail a Will save must choose between action or move each round; have their move speed halved; and get -2 to AC and Dex saves. Very powerful against melee foes if you've got a ranged-heavy or skirmish-oriented party, not so much if you've got heavy melee guys of your own.
So it will hit all four of the hypothetical fireball targets, right? Let the melee heavy PC's close on the 1 in 4 that made his save and quickly dispatch that target. The ranged characters can focus on the other three, and I assume nothing stops our melee heavy hitter(s) pulling out a bow to join the mopup. Just like the wizard will often just stand back (or cantrip, or crossbow) in the mopup rather than waste a ,ore valuable, and limited, spell resource.
That's why you play an evoker, allowing you to "shield" a number of targets equal to 1 plus the spell level. Those creatures automatically save against the spell, and if the spell would normally deal half damage on a save, it deals nothing.
Again, seems like the evoker gets major bonuses. Assuming comparable bonuses for more subtle spellcasters, how do they compare?
In any case, this is more an illustration of my own lack of 5e knowledge than anything else. My simplistic point is that Blasting should be a viable option. It appears that it is for a focused Blaster. If the game is shifting to force spellcasters to focus on a specific area (such that this Blaster's spells other than Blasts will be about as useful as that Fireball would be to an Illusionist who can't exempt teammates from damage, gets no bonuses, etc.), then we have that balance. Seems like 5e will focus on less versatile wizards with more flexibility available for each spell, rather than a wider spell selection, which is a valid approach.
True. But there's no differential recharge rates for the most part pre-4e. Things are either use-limited or not, and you asked about the importance of making a distinction between short and long recharges. I don't think that distinction is very meaningful in most situations.
There's also the difference between a short fade rate and a long fade rate. If we have one encounter a day, a 3e Bull's Strength (which lasts hours) and a 3.5e Bull's Strength (which lasts minutes or rounds) are both the same. If we have half a dozen encounters spread out over the day, that duration change is a lot more meaningful.
Nor mine. But between four and six encounters before resting for the evening? Quite common. The norm, in fact.
3e? Sure - six seems at the high end, even. But I can't blindly blast off my heaviest artillery in the first encounter if I expect a few more today.
By the time well-constructed spellcasters hit mid-level, they typically have enough powerful spells at their disposal to use one or two powerful spells at the beginning of an encounter (often only one is necessary) and follow those up with less powerful (though still extremely effective) spells for the rest of the combat.
If I read the analysis above correctly, one powerful spell for each of four encounters (assuming we consider a 6th level spell "powerful" for a caster with the capability of a 9th level spell - not sure what his higher level spell options are or how they compare to that 11d6/12d6 Fireball) and a pack of weaker ones. Care to spell out a spell load for that 7th level wizard whose fireballs are going to be an effective threat to CR 7 opponents with 120 or so hp?
Are there some more knowledgeable 5e commentators still concerned, or have they been swayed? I'm on the 5e fringes, so if those with a greater understanding of the 5e mechanics are sold, I'm probably sold too.