I liked a lot of Aliens, but it kind of detracted from the original, and I don’t think much would have been lost if it were never made.
Does this really matter, though? I’ve never understood the thought process behind disliking the very existence of a movie. If you like a lot of the movie, why does it matter (and why should you let it) if it detracts from the original?
EDIT: I guess I should add the Alien to my list of movies that I enjoy but don’t understand why they’re so unbelievably fantastic. It has great stuff in it, but at its core it’s basically just a bunch of characters constantly splitting up until they’re all dead. Plot-wise, Aliens is superior in my opinion.