It's really important to call out context 👍
Ah - you also need to use it to 😘
I guess what you (me and maybe most people) don't have is context. It's not normal for someone to get up, on a live show, in front of an audience of your peers, and slap/punch someone. So with that in mind, there is probably some other context that we are not aware of:
Chris Rock has taken the mick out of Jada before - may be there is some more to this history.
Jada has written before on the issues she has with suffering hair loss - do it's obviously something that affects her not just professional but personally too.
Maybe, before they came out, Jada was not doing well. maybe she was really upset. Maybe she has depression?
Maybe Will was laughing along because he didn't hear properly (as in "I must have heard him wrong") and maybe he didn't want to cause a scene - perhaps when looking over at Jada and saw that she was upset, he realised that this is maybe not the time to stay quiet.
Or maybe Will Smith was drunk/think's he's a tough man and would sort of Chris Rock there and then.
Personally, if someone is going to make something that personal a "butt" of a joke - on live TV in front of a load of your peers - they also have to take responsibility for what they say. Would a strongly worded statement in the papers make a difference - would an apology from Chris Rock work. Would everyone forget the joke and remember the apology.? Dunno. Would I have done that - it's a hypothetical question because I don't live that context (and never will) - but agree that hitting people is not the answer (which is probably why Will apologised). But it depends on the context.