Because that's like, Vegeta's M.O. Acts all haughty and shit as if he hasn't been repeatedly humbled hard af throughout the series, including him doing just that to characters that are stronger than him. The only time I ever really go with the flow is when it is very clear that he's confirmed to be stronger than the enemy, because for me personally, Vegeta is at his most entertaining when he knows he's going to win. Obviously yes, his whole pride thing is a big part of why people like him, and being prideful in a universe like this isn't inherently bad or anything, I've just... always found it hilarious is all. Vegeta may come across as him pretending that earlier humiliation didn't happen, but I sure didn't. In isolation of course, it was certainly cool.
Also it stuck out more with Black because he wasn't really all that injured by the beatdown. A mix of DBS being reluctant to show proper damage, as well as Black just being that strong (He was still stronger than Vegeta, wasn't he?) I suppose.