Wait, what? In 4E, they explicitly define the role that each class fits in. How does this tie in with the "notion that every class has to be equally effective at the same things"?
Are you suggesting that the 4E fighter is designed to be as good a healer/buffer/leader as a 4E cleric? That a 4E ranger is designed to be as good at crowd control/area effects as a 4E wizard. I'm not seeing that.
It seems to me that explicitly defining class roles, and designing classes with the roles in mind, should lead to less overlap of abilities, not more.
In 3.x, how many people could heal? Clerics and people who threw a ton of points into the Heal skill. In 4e, *everyone* can heal themselves, so, yes, the fighter is equally effective as a healer as the cleric.
In 3.x, everyone used Str as the basis for melee attacks and everyone used Dex as t he basis for ranged attacks. Most of the time, the wizard had a crappy Str and probably a marginal Dex. The rogue generally was better at ranged attacks while the fighter types dished out the pain up close. In 4e, everyone gets to pick their favored attribute to attack "Wis vs. Ref, Cha vs. Will." Now - everyone is equally effective at attacking because they can all use their best atttributes as the basis of their attacks.
The point is - in 4e, it seems that all of the parts are interchangeable. I don't particularly like the idea that a party consisting of halfling rogues should have an equal experience as a mixed party of different classes.
In my first 4e game (sample) ever on Tuesday night, we had an eladrin paladin, a human wizard, a rogue (run by the DM), and a halfling cleric (me). There was no distinction between them. In an example fight from keep on the shadowfell, it was "attack, be attacked, heal self, be attacked, attack." The only difference between us was the name of the power and whether it was d4, d6, or d8 depending upon at-will, encounter, or daily.
What I *did* get out of it was houserules for my 3.x game - 1-1 diagonals, simplified cover and concealment, etc.
Again - if you prefer 4e, have at it. I just prefer my D&D to feel more distinctive and not so cookie-cutter in its approach. Granted, the unified mechanics in 4e lend themselves quite easily to porting to a MMORPG...