Many years ago, I had to take part in a public speaking course through work. We were all tasked with creating a presentation on the subject of our choice, with the purpose of making the audience feel a certain way.
One of my colleagues did hers on alopecia. No one in the room had ever heard of it. She showed pictures of her young daughter, with a full head of hair. Then went on to tell us how years later (daughter in middle school) her daughter inexplicably started losing her hair.
As she was telling us the story (her daughter was in her 20s at this time), she struggled to keep her composure. By the end of her presentation, everyone in the room was crying.
I like Chris Rock. And I like Will Smith.
Chris Rock made a bad decision to take such a low hanging fruit to get a laugh at the expense of Will Smith's wife. He can be funny in a gazillion ways without doing that.
Will Smith reacted. He reacted like any man who loves a person who is disrespected the way his wife was. It doesn't make it right, per se. But it does help explain his actions.
Personally ... I would have done the same exact thing ... even if I knew it wasn't the right thing to do.