I would never even attempt to defend Kanye West as a person, as he's incredibly arrogant, and far too sold on his own importance. That being said, I find that many incredibly successful people are eccentric, quirky, bizarre, arrogant, etc. Is he really that different from other wacky musicians/artists? I don't think that he is.
To completely dismiss his music betrays the fact that you either are only familiar with his singles and features on other artists' singles, or you aren't a fan of hip hop period.
He has unquestiongly produced some of the most powerful and "catchy" (not sure why you devalued a song's catchiness) tracks in recent hip hop memory. From "This Can't Be Life", half of the Blueprint, Kweli's record "Quality", Common's "Be", Lupe Fiasco, and on and on and on. He's not an amazing emcee, though I do like his self deprecation, but he is an incredible producer/arranger.
Other than J Dilla, and maybe Hi-Tek, he is probably more responsible for the resurgence of soulful hiphop than anyone else.
He's not making incredibly difficult, or esoteric music, but not everyone needs to be Def Jux to be worthwhile.
And yes, he has done an amazing job selling himself.