1) Hill is a bit of a boring jobber of a fighter - a boxing-based guy who never boxed and doesnt come from a background in BJJ or Judo or wrestling, which is fine but it isn't very exciting - as compared to Jiri's crazy haircut, suicide rope neo-samurai shtick.
2) Hill's Helwani grift was really painful. He was totally out of line there and went all in dissing Ariel in a way that just made himself look stupid and mean.
3) Nobody remembers any of hill's big fights because he hasn't really had any - he has one win of any gravity against an ancient Glover, in what was to be Glover's last fight before an arguably overdue retirement.
4) He talked shit about Alex not being on his level, which is a plainly stupid thing to say, especially given #3 above, so people were excited to see him get his come uppance.
5) He seems to have beaten up his brother.
6) general disrespectful, adolescent behavior. He lands in the sweet spot with his bullshit. He doesn't go way overboard in a comedic (chae, connorl) or cringe (Triple C, Colby) way, he is just enough of an asshole that he comes off as a prick, but it doesn't generate any hype and seems to come from a place of being a dickhead rather than trying to hype up the fight or intimidate his opponent.