I also don’t think one of the major messages of Canto Bight is “don’t abuse animals.” Obviously, you shouldn’t abuse animals. You also shouldn’t be a war profiteer. Pretty sure that was the primary thematic function of the trip to Canto Bight. Finn loves the decadence of the city at first, and is provided an opportunity (in the form of DJ) to put his morals on pause (or abandon them altogether) in order to enjoy it in the future. DJ’s function isn’t to replicate Lando’s character, because Lando and DJ are basically nothing alike. Like Hello very smartly pointed out - DJ’s function is to be the devil to Rose’s angel on his shoulder. “Look kid - it’s all rigged. It’s all a racket. You can be a sucker if you want, but why not be smart and above it all, like me.”
I was honestly surprised that Phasma didn’t come back for Rise of Skywalker though. Abrams could have easily brought her back, he just… didn’t.