It's all subjective of course. But SMB did exactly what it was supposed to do. It gave the fans of mario a movie they wanted to see. That isn't a bad thing. It's Mario, it didn't need to be the Shawshank redemption. Soul, Luca, Raya, Encanto, turning red ranged from OK to extremely meh in my opinion. Were they lesser quality than Mario? Depends on how you look at it. They aren't better because they try to have a grander message. Mario is a better film in my opinion because it accomplished exactly what it was supposed to.
You call Mario mostly nostalgia bait. That's been the ace card Disney has been trying to play as a company for how long now? The difference is that Mario pulled it off and the fans are loving it. The Star wars sequels needed more of that nostalgia bait as you call it. They sold us on nostalgia, but we all know how that went. I would place money on if the sequels were Luke, Han and Leias story, star wars isn't in the spot it is now.