Please dont destroy D&D for me......... again. Not being reactionary or dramatic, just telling you the truth, maybe my reaction below will shed light on it a bit.
My illusionist isn't a controller. He's a fun little gnome, who plays tricks on people. Often he's completely useless in combat, because the undead consider him an idiot, so I as a player have to work extra hard to make sure I'm not holding the party back. I think of clever ways to interact with the environment or the encounter to have an effect, and I expect my DM to craft encounters where there are a VARIETY of ways to overcome some (but not all) encounters. The DM doesnt do this because I chose an illusionist, he does this because thats what DMs are supposed to do.
My illusionist is a challenge to be as powerful in combat as my fighter comrades. Thats OK, because I'm a kickbut usefull mage in social situations, bartering, making deals, convincing people to help us, overcoming obstacles and even exploring with my side spells. Still in other situations my phantasmal killer, or mirage arcana are clutch spells. Pit me against an army of humans and I may just have 500 soldiers running before the fighter draws his sword.
By making me a controller you scare me that you will simply force me into the same template as everyone else (as was done in 4e). I want to be weaker in some situations, thats why I chose an illusionist in exchange for power in other situations. Cruniching numbers to make me useful in combat will not "unite" anyone.
And if my DM is a strict combat oriented undead heavy DM? Thats ok, when I die I roll up a barbarian, or try again with the illusionist. I much prefer you not redefining the illusionist to play well in his world. In fact by redefining classes to play well in his world, you encourage it to be the only one a DM can imagine. Leave the combat challenged illusionist alone, it will help make the game more imaginative.