I don't think it was a very funny joke, but I don't think it was below the belt either; to me, it's a compliment. If I think of the film GI Jane, from my understanding it's a story of female empowerment against brutal odds. I wouldn't look at a timid Julie Hagerty in Reversal of Fortune and think she'd could play a badass soldier, but I look at Jada Pinkett Smith in Collateral (a film I freakin love) and think Yeah, that's a badass lady who could play a badass soldier. And shaving her head just underscores that feel. I mean, take a look at Alien 3. Another shaved head performance of a lady being a badass. I don't think Sigourney Weaver is a very good actor, but I do think she can play a badass, and I think that's a compliment.
I haven't read anything about Jada Pinkett Smith's struggles with her looks over this, but I'm not seeing a lady who's suffering here. The way she presents herself in public seems very very confident. She posted a damn video shoot of herself in that enormous dress just before the Oscar ceremony, for god's sake. I'm not condoning shitting on spouses for no good reason, but I think it really was read the wrong way. And even if it was meant as a roast, again, I say that's a form of comedy in itself. Should we shit on the ghost of Don Rickles? What it seems to me is she might take herself too seriously, and Will Smith, for all his natural acting talent and his natural charisma, might just be publicly facing his inability to deal with being a cuckold, and, coupled with an enormous sense of entitlement, has no problem dominating a situation to play out what he should be facing with a therapist. It's messed up, but I just see a misdirected psychological outburst. I love some of Denzel Washington's performances (everybody go watch Glory now!), so I was wincing to learn that he was "counseling" Will Smith right after. How about running over to Chris Rock to say, "Hey Man, that was fucked up."
For his part, I thought Chris Rock showed a ton of class, and I couldn't believe, for as obviously flustered as he was, that he could actually make a pretty funny joke out of it, even while he had visible trouble stringing together sentences, probably from an insane adrenaline rush. I respect him both for keeping his cool and for essentially saying, Dude, that was a dumb joke. Why the hell are you overreacting like this?