I completely agree, but I think it's sort of like tradition atp for 80's horror movies, and makes it even more fun to watch them in my opinion.
No movie franchise needs that many movies, especially from one that was supposed to be a stand alone(Texas Chainsaw Massacre lmao) but it's like how almost every movie you watch that has a sequel your already expecting it to be bad. If I start a franchise I have to watch all of them even though I know it's gonna suck, just because that's the fun of it I think, and I also think a lot of producers figure capitalizing off of these nostalgia inducing movies will make them a lot of money, and it does lol, I mean look at Scream, Evil Dead, Final Destination, and Chucky. All cult classics but have so many different movies and crazy plots from movies, that would otherwise be standalone.
But I think they do it atp for the love of the game, I mean there's a Jason/Friday the 13th movie where he goes to Manhattan, and one of the last Nightmare on Elm Street movies we find out he has a daughter?? It's so weird, but it's a really fun way to go back and see how far the producers are willing to go. That's just my opinion lol, it's overkill but it's fun.