Bedrockgames
I post in the voice of Christopher Walken
Why is "chance to contribute" automatically meaning "All contributions are equal"? The dumb fighter can try to contribute in the investigation in 4e because his base abilities might still allow him to stay in the game. But, at no point is he going to be as effective as Brighty McSmartypants the Bard, simply because the fighter's abilities aren't as good as the Bard's.
I have no issue with everyone having a chance to contribute, if that is what you want in your game. If you prefer everyone having a chance to succeed in 3E you simply open it up to 20s being auto successes on skill checks (now everyone has at least a 5% chance of success on any skill). But it sounds like people want equally meaningful contributions to be available in all situations. Though maybe I am misunderstanding what people are saying.
The problem comes when the rules say, "Sorry Jim, you just aren't tall enough for this ride, no matter what". And, worse, it might tell Jim that despite Jim not making any choices at all - a rogue facing a non-sneakable opponent for example. Or anyone else trying to find a DC 21+ trap in 3e. They simply cannot do it, nor can they contribute in the slightest.
It depends, there are tasks that will be impossible for some unskilled people to achieve. All that means is you either find someone in your group who has the skill to do it, or you find another way around the problem. If a gorge is too wide for anyone to jump, you go another way.
Personally I have no problem with this. The GM sets the DCs here. As a player I have no problem with there being traps only the master rogue can disarm. And I have no problem with their being walls only a master assassin can scale. It isn't going to bother me if my fighter has to wait out that one tiny moment while the rogue shines.
Also just because the rogue is the goto guy in this instance, it doesn't mean I can't make a contribution. I just can't scale the wall or disarm the trap.