First off, apologies for the length of this post - I've been offline all week and just finally read this thread.
The thing about LA/ECL is this: It never really worked.
Oh, you could play with it, don't get me wrong. And you could have fun with it. But the truth is, it implied a level of compatibility and equality that it didn't really deliver.
Your argument (and correct me if I'm wrong here) is that LA/ECL is broken and should be tossed out, but I disagree. The
concept of having an LA is good, but the
implementation sucks. It's like the CR system - they eyeball it instead of coming up with a hard and fast system (or at least a freeform system like Gygax') for figuring up what a creature's CR should be. Also - and this is something that I think everyone missed until Upper Krust found it - XP shouldn't be based on CR - it should be based on the EL. A CR 5 creature is not a serious challenge for a party of 4 5-th-level PCs - it's more like a challenge for a party of L3s. Thus it's an EL 3 encounter, and XP should be awarded appropriately. If they'd come up with more accurate LAs, I think the system would work a lot better.
Mind flayers, for instance. Does anybody here really believe that a mind flayer is equivalent to a 15th-level character? Really? I don't. And my experience doesn't suggest that it is.
Mind flayers are LA +15?

I think they did it wrong, or at least, as I said above, the implementation is wrong - once you add class levels onto a monster, you take the LA (which should always be equal to or higher than CR) instead of the CR and add it to the class levels for the final CR. So, the mind flayer Sor 9 would be ECL 16. Templates work the same way - if it's applied to a monster, you use the CR modifier, if it's applied to a PC, you use the LA.
I also think the mind flayer's a bit overpowered - SR 25+ class level??
I see a lot of people that want a high congruency between the rules for monsters and characters so they or their players can play monsters. While this is definitely a cool option, I think core D&D needs to be created to serve the vast majority of its player base who don't expand their racial options past your basic fantasy archetypes. D&D has never been, nor should it be, a fantasy RPG toolbox and as such monsters need to serve as monsters first and foremost.
Amen. Make monsters be monsters, and give rules (in the same book or a later one) for people who want to play monsters-as-PCs. I don't think the two are incompatible goals, though - see my comments above.
And this is also a critique I voiced in my blog (see .sig) regarding the current design ethos at WotC: They spot a legitimate problem and then solve it in a way that doesn't make any kind of sense to me. (See, also, Mearls' write-up of the rust monster and Noonan's comments regarding non-combat abilities for monsters.)
The darkness spell comes to mind here...
The solution is to say to the player, "Spend your skill points and achieve detailed results." And to say to the DM, "Pick a number of class skills equal to X + the character's intelligence bonus. Their skill bonus is equal to the max ranks in a class skill."
Again, you can say the same thing to players and DMs: "Spend your skill points and achieve detailed results." The only difference is that DMs would have an extra sentence: "If you have some skill points left over after filling in all the skills, then ignore them, unless it's a recurring monster/NPC, because it's only going to be used for 1-2 encounters anyway."
In any case, it does sound like the mechanics on stat design are not going to be as transparent as they are in 3E/3.5, so "gearheads" like Mr. Cooper (I think that's the term, and it's not meant disparagingly) are going to have a harder time checking up on stat block accuracy.
Amusing as that is (I laughed out loud when I read it), I don't think that's the true reason they're doing it like this. It seems to me that, like the magic item creation system, they want something more free-form and flexible. The side effect of this is that, yes, it'll be harder to "cross-check" stats, skill points, number of feats (if any), etc.
Personally, I think the current method is a good one - you have a series of formulas, plug in the numbers, calculate the CR, and BAM - you've got a monster. It's boring as all hell, because despite the inherent creativity in thinking up the monster and its abilities, you're just plugging numbers into a table, but it's very easy - I can do a monster in under an hour, most times. I've been designing D&D stuff (monsters, spells, and whatnot) for almost 20 years, and I have to say, it's a LOT easier than 1E/2E - back then, you had to look at existing monsters of the same/similar type, guess at stats, HD, damage, etc., then hope you didn't get the thing horribly unbalanced .
So grant it to PCs at that level.
Yuck.
I'm sorry, but that really doesn't appeal to me. I'm not a tight-sphinctered DM who doesn't want the PCs to have any cool toys. But as a designer, as a writer, as a DM, and as a storyteller, the notion that anything a monster can do must be available to the PCs is a non-starter. The monsters and NPCs are, or at least can be, plot points. And most iconic fantasy involves at least some element of heroes finding the way to overcome or get around an ability they don't understand.
We agree on this point, at least. I hate the "NPC X has it, so why can't I?" philosophy. Some things
should be restricted to NPCs or monsters only, for whatever reason - usually because in the hands of a player, usable all the time instead of in limited (and controlled) circrumstances, it's overpowered (like the Frenzied Berserker - that thing should NEVER be used as a PC PrC for many reasons, chief among them that it's not a party-friendly class).
It might also finally be true that you can build an expert npc with +15 to a skill or whatever, without them being 75 HP tough guys that can take out a whole party of low level characters.
That's easy to fix - simply rule that NPC classes don't gain HD, saves, or BAB - just skill points and stat boosts. How often is an expert or commoner ever in combat anyway? If they are, they're cannon fodder - the ogre smashes the poor farmer to pulp with his club, the smith gets shot full of arrows, etc. - they're just story elements glossed over by the DM. On the off-chance that a PC wants to start off as an NPC class (we did that in one campaign) or a DM wants to have a multi-class NPC, then he can use everything. Or not. I do think that NPCs should gain "levels", though - XP is a measure of life experience, knowledge, and memories, and even simply living would gain you levels, like someone suggested. Being a crafter would gain them faster, because you're learning how to make stuff, new techniques, etc. - this is reflected in the gain in XP, which correlates to the increase in skill points.
So, is it possible to make monsters either better, faster, more easy to run, or cooler by sacrificing consistency?
I'd argue that the answer is yes.
Is it possible? Yes. Is it desireable? Maybe... but having the same/similar design systems across the board makes DMs/game designers' lives easier, because they don't have to look up (or memorize) one set of rules when they're working on NPCs, and another for monsters - they can use basically the same system.
B) We no longer have to lock monsters into the same "1 feat/3 HD" progression that PCs follow.
An easier solution, instead of assigning a free-form system, is simply go like they did with skills - each monster type gets a different feat progression. Undead, for example, would get 1/4; constructs get 1/5; humanoids get 1/3; etc. In this manner you a) provide a unified,
consistent framework for monster design; b) can better account for bonus feats, and c) can customize the amount of feats a monster gets based on its "role" - constructs, for example, aren't very bright and don't need a whole lot of feats, so they'd get fewer than a humanoid (which, incidentally, is more likely to be used as a monster race, and should thus be closer to the PC norm). If a player wants to take a monster race that's sub-optimal in terms of feat selection, well hey - them's the breaks. Templates will still break the mold, so to speak, because they don't have HD, but that would be covered by the LA.