There's a big reason why studios are likely happy with superhero movies, especially the Marvel films.
Obviously Marvel studios has produced some surprisingly amazing movies out of franchises and heroes that didn't really have a huge following to begin with. (Guardians of the Galaxy, Ant Man, Doctor Strange, to name a couple). And obviously the movies seem to be making ridiculous amounts of money by packing theater houses.
But there's another reason why superhero franchises are so popular with studios: the merchandise sales are off the charts.