I can talk about some blockbusters. I like the Marvel's MCU movies (though each one progressively less, my favorite still being Iron Man 1). For me, they have a near-optimal composition of plot cadence, special effects, music and cliches. They're usually pretty polished. I find them good for light enjoyment, and since they also appeal to a very wide audience, it's something I'll immediately get to talk about with a lot of people, or something I can watch with my SO without worrying it'll bore her out of her mind.

It's fast food of entertainment. A composition optimized to appeal to senses, even though it's of questionable nutritional value. I think it's fine from time to time.

Are you asking us to explain or generalize the behavior of billions of people? How much time do you have because there's about a billion reasons

Assuming the Marvel movies fall into the category you're talking about... I adore the Marvel movies, as does everyone else I talk to about them. They're fun to watch, I'm fully vested in the characters (which, to some extent, is based on my reading of comic books so many decades ago), and the shared storyline/world is great.