I don't hate guitarists. Actually, I have ENORMOUS amounts of respect for Matthew Bellamy (Muse.) I LOOOOVE his guitar work. He's inspired me to try playing guitar (even though I haven't gotten around to it yet).
+1
Many will disagree with me here, but I think Muse is a great group of musicians. I look forward to their next album.
Anyway, my 2 cents, if I may:
Guitars are no more inferior than keys or drums or bass. However, for different players, it's a decidedly different story. There are simply better musicians (and people, for that matter) than others, and some of those people just happen to play guitar.
There are bad guitarists, bad bassists, and people who are bad at any instrument ever invented. I guarantee it.
I think I might agree with the psychological effect of the term "lead guitarist", previously mentioned. Seriously, why don't we have terms like "lead drummer", or "lead keyboardist", etc.? They would be accurate, wouldn't they?
The term should be fine, so long as it isn't allowed to go to his (or her) head. A band should be a team, not a few solo artists who happen to be touring together.