I don't agree with your criticism of monster roles. I find it a useful shorthand for working out how, mechanically, a monster is going to play in combat.
It's not really just a useful guide, but a prescription. A monsters role + level is what you plug into the system math to get the monsters stats. There are certain damage levels and effects and abilities that are appropriate for each role and monsters of that role have them. Soldiers have defender type mechanics. Controllers either inflict status effects, move people around or do a lot of multi-target attacks. Brutes do lots of damage and are easier to hit. Skirmishers take advantage of mobility and combat advantage.
These aren't really general shorthands or clues for the DM about how to run the monster. These are the mechanics of the game and how it all works. These roles are directly tied into the whole scaling by level system as well as encounter design, xp budgets, etc.,.
And then on top of that, monsters are all essentially based on the standard level scaling system. They're all variations of this:
http://slyflourish.com/master_dm_sheet.pdf
Anyway...
It's sort of funny. Back around 2002/3 I ended up getting burnt out on 3.x and ended up getting into a lot of Forge type games like The Pool, My Life With Master, DitV, etc.,. I thought trad gaming with it's task resolution was the problem.
Then in 4E came out and I really appreciated its focused design and particular type of play it produces. I played and ran it a ton, but got sick of the focused type of play it produces.
I think my issue all along is that I actually like trad type play with it's focus on a continual narrative fiction that emerges out of sequential task resolution called upon by disagreements of success of individual actions in the narrative. I just didn't like how 3.x didn't do that as efficiently and as neatly as it could have.
Deep down inside I think I'm an ardent "right to dream"er and 4E just isn't doing it for me anymore. With it's game play focused approach and it's defined combat roles for PCs and monsters alike and all the various issues I have with its refresh mechanics and reward cycle.
I think at this point, perhaps my default position should be to assume that like the rest of WotC's products, D&D Next won't hold my interest nor fit the type of play I'm looking for at the table. If I get pleasantly surprised, then great.