Re:Obvious Missing Option (Score 1)

What's so bad? He only has two onscreen personae - variants on the Fresh Prince, or a Tom Hanks-esque earnest Oscar performance. Sci-Fi roles - I, Robot excepted - fall into the latter.

Personally, I find the Fresh Prince character arrogant and irritating, especially when he shares the screen with Carlton. Also, he's confessed in interviews (sadly not online) that he had no acting experience when he was signed to the role, so basically played himself - thus I feel justified in taking a dislike to him personally due to my dislike of the character (and there is some corroborating evidence that he's an arrogant asshole in real life[1]).
Finally, a lot of the raps he recorded for his various film roles are unacknowledged rip-offs (witness [2]).

1: http://www.bvbuzz.com/2009/06/17/sitcom-saga-tv-mom-claims-will-smith-was-no-prince/4
2: http://www.youtube.com/watch?v=td25kTqvl1w