After playing 4E for quite some time now, it seems plain to me that 4E was WotC's attempt to try and bring new players into the mix. It was a noble pursuit and I give them kudos for that. More so, however, it was an attempt by WotC to write rules that force characters to be involved. Now, stated this way, one can really see WotC's aim. WotC claims they wanted every character to be involved in the game at every level--whether it be combat or roleplaying. Every PC should have something to do.
Here's a different philosophy--every PC should have something to do if they want. The 4E DMG gives a negotiation as a prominent example of the new "skill challenge" mechanic. This mechanic essentially pulls all of the characters into a dice-rolling scheme to see if the negotiation is successful. No longer will one PC be the spokesperson for the group, according to this mechanic. Delicate negotiations SHOULD include the blunt and brutal barbarian right? Listen. If that barbarian wants to be part of the negotiation there are a ton of roleplaying actions that character can do. For starters, ALL of the PC races/classes speak. If the PCs are of a like-mind and have similar adventuring purposes, the negotiation will not break down if the "dumb" barbarian opens his mouth. All the party needs is a head PC to introduce the barbarian. "My strong friend here will tell you his side of the story, but I will caution you. His tongue is sometimes harsher than his looks."
Was that so hard? What king is going to be outraged at the harshness of a character after being told it's normal behavior for that character?
My point here is every PC is responsible for their character's level of involvement. The same is true for combat scenarios. The party had a rough day of fighting when the wizard pulls out the wand of magic missile--but that's why he has the wand! A smart player bought that wand so he would always have something to do. You don't need a rulebook to tell you that.
I would argue here that 4E really was an attempt to codify imagination. More structure helps the weak minded grasp concepts. 3.5 was a much more open gaming system that put the creative license in the hands of the players instead of in the core rulebooks.