They make money on them.
Young people, if they are not old enough to drink, or don’t have hobbies, have little to do on the weekends except go to the movies, and they flock to these.
Young men feel like they can’t afford to date, young women don’t like to go out alone, or are afraid to hang out in bars, and so the uncoupled flock to these things. And yeah, they are not terribly fine or entertaining for adults.
Just my opinion.
I don’t ever go to these type of movies. I much prefer a great classic story well acted and well told.
YMMV