Being perfectly honest, the popularity of super heroes seems to be shifting. DC has been getting a number of complaints with superman and batman, while Marvel has gained nothing but high praise for their work. And all the works either involve a group of heroes, or a solo hero who is also part of a larger group elsewhere (avengers). So the idea of superman being "thee" hero is getting weaker, the popularity and fan base just is not as high anymore.

I will fully admit that any super hero RP though, may you go the super man route or the avengers route has serious power scaling issues. It would take a skilled and controlled group of players to properly handle and manage abilities and their use. But at the same time, let's remember the whole point of the genre is for insanely powerful people. I can completely get why that may draw people off (and is probably a big reason for people not doing hero rp's). But I still find it to be a more popular topic than anime (unless if you look at free, free tends to go anime crazy).