For the same reason that the more ghastly or depressing a scene is, the more people are going to make jokes out of it, the more cutesy and light a series is, the more people are going to create a "dark twist" version of it. I.E. A cutesy Baby Cthulhu or all these moe xenomorphs or all the Mami Mogu Mogu gags, versus all the people who want to make "hardcore" My Little Ponies stuff or any sort of "Darker and Edgier" remake.
