Why not? Fantasy fiction is replete with legendary "sidekicks". For some reason this seems to be difficult for certain people to understand, but most of us are not interested in being the alpha dog. Sidekick, companion, support character, noncombatant, and a variety of other roles are entirely valid choices, ones that if anything we should be encouraging.
After all, what kind of game would we have if we had parties of four or more people and no sidekicks? That's a recipe for disaster.
Moreover, in D&D this dynamic is well-established. You don't see Caramon bitching that he can't do the things that Raistlin Majere can, and indeed the latter values him tremendously. Nor does the god-wizard (i.e. Elminster) cause problems. People are still lining up to play Drizzt clones despite the fact that he isn't a "CoDzilla" (and if there's one setting that emphasizes the power of spellcasters, it's FR). In fact, to enforce the kind changes in class balance you're getting at, you'd pretty much have to tear down the D&D aesthetic, and all of its settings. As you may be aware, this was actually done, and it failed to produce the desired effect, never mind the cost.
No, it doesn't. The people at the table are the ones responsible for balancing the game. If they do a poor job, the results will speak for themselves. If they do even a half decent job, the game will work, completely irrespective of what rules they're using.
