Ryujin
Legend
I posit that this is not a problem with "low ability scores" per se, but rather a problem with the mechanics of the Skill Challenge.
People can't just "sit out" combat, they shouldn't be able to just "sit out" other challenges.
Why shouldn't they? The original mechanic, that required everyone in the party to contribute to a skill challenge, was something I thought had to be one of the dumbest things I'd ever seen. Everyone doesn't have the same experiences, nor skill-set. People specialize. The Eladrin Wizard is as unlikely to have learnt spelunking, as the Human Fighter is to have learnt ancient Elvish. I don't want the ham-fisted Paladin monkeying around in the carefully balanced trap that I'm trying to disable, as the party Rogue.
People who don't have the appropriate skills can try to assist but to have them take a primary role, in something with which they have no knowledge or skill, is begging for failure be it in real life, or in the gaming world.