Using the Kings, who haven't made the playoffs since 05-06 and are arguably the worst run team in the NBA to make your argument isn't the best example.
Gallo is 32. Thats the right role for someone of his age. Rozier is 27. When Love signed that deal, he was a starter and LeBron had just left. Plus they're stuck with that contract due to his health. Completely different situation than Rozier and the Hornets.
He's being paid like Brogdon, Conley, VanVleet, Gary Harris, Lonzo -- all starters.
Two things can be true. This is a great move for the Hornets as Rozier showed he's worth that type of money. But this is far from ideal for Bouk. Unless there are injuries, he won't be getting the minutes he needs to ideally develop. I'd rather have him start playing 30 min than playing maybe 20 min behind multiple, more established guys. He isn't some "raw prospect" that needs that type of time to develop (like a Kuminga on Golden State or Giddey who OKC drafted). While not a finished product by any means, a lot of his game is NBA ready and sitting on the bench doesn't help that.
It's not a death sentence by any means but there would have been better opportunities for him and Rozier signing for 4 years cements that. It's just not what you want for him, but hopefully he is even more motivated by this and earns his spot in the league.