Just to have at least one counterpoint in this thread, but I loved the ending. Much, much better, IMO, than a non-meta epic fight with LeChuck, for example.
I took it as a very interesting and profound discussion about the role of games and fantasy in our lives as adults after playing it from a different perspective as kids. The dialogs during the ending are very well thought and thought-provoking. The role of Elaine in it is special.
I loved the whole game, but the ending brought it to a complete new level for me. It’s probably something that I’ll want to play again a few years from now.
My recollection is that the negative reactions to Return mostly seem to come from the camp of "MI is a proper pirating adventure with some funny jokes in it", which you can kind of hazily reinterpret the first game as, and definitely Curse can be slotted into that. Like, there's a whole manosphere-they-ruined-my-heroes element going on with that interpretation, where Guybrush has experienced "Kirk Drift" and turned into a badass womanizer who can defeat LeChuck like some kind of cunning JoJo character.
But really, Ron Gilbert always wanted it to be critical and at least a bit deconstructive of all the pirate tropes: Guybrush never gets taken seriously as a pirate, the way in which he pirates is bizarre and unglamorous, and the dialogue follows a sort of knowing "NPC normalizes any choice the PC makes" railroading back into the puzzle gameplay. Gilbert just got more clear about doing that in the sequels, and I think Return is a great capstone to that.
After playing Thimbleweed park, it became clear to me that Ron's a huge fan of David Lynch, whose films often explore Buddhist or Hindu themes of reality as a dream we create inside our heads. I think that this theme appears in most of his games, and the endings of MI2 and Return are no different. When I finished MI2 as a teenager, I felt cheated too, but now as an adult that has spent a lot of time meditating and exploring eastern philosophy, I think there's a lot more to it than I could appreciate at that age.
He's made the ending he always wanted. The "secret of the monkey island" was supposed to be that it was all a park attraction all along and that was why there are so many anachronistic things in the game.
He already did the "it's a theme park" ending in MI2 and it was fine. Not tbh my favourite part, but fine in that context in that time. There was something about the new one which was appallingly "fuck you for still liking Monkey Island".
I couldn't bring myself to finish Return either. Which is a huge bummer, since the first couple games are near the very top of my list of favorite and most (personally) influential games ever. But the nostalgia tour and nonstop callbacks to prior games, rather than actual new content, didn't really do it for me.