Why watch the version trailers?

I'm curious why people watch the trailers for a game that they are already actively playing anyways and also contain some spoilers, like Phainon stabbing Mydei, Flame Reaver attacking Tribbie, etc.

If I watch trailers, then I do so only after finishing the respective version's main story/content.

It's not meant as a "My way is superior, so why are people doing it differently" or so, but genuine curiosity