I don't think it is a bad film at all. Not unflawed, and nowhere near the same league as Across the Spider-Verse, but certainly solidly entertaining.

To your broader point: The big problem in mainstream Hollywood is everyone cynically trying to do "universes" the way Marvel did. What works for them won't necessarily work for everyone else (and indeed, I'd argue it's no longer working for Marvel in any case). From an artistic perspective, the best way to make a good film is to make a good film that stands alone entirely, without being dependent on "franchise building".

Also, I'd welcome a ten year moratorium on superhero films. That won't happen, but I can dream. :)