[CMIII]

My understanding is it is all a timing issue. Way back before X-Men came out Fox bought the rights to X-Men (most related), Fantastic 4 (most related), Spiderman (most related), Ghost Rider (most related), Daredevil (most related), Silver Surfer and Glactus. Over time Fox has a certain amount of time to produce movies with these and that cruch grew when ABC/Disney came into the picture. I do know that Fox released the Hulk (prior to 2005 after the Ang Lee flop) and that Silver Surfer and Daredevil were let go a few in the last few years. It takes 2 years for a Movie to go from Production to Release (unless your Peter Jackson and you make them all at once and release them every year).