Good points, all.
It's almost as if FOX has a problem identical to Warner Bros. That studio is using Batman and Superman as the very "crutch" BMM mentions--for the greater part of nearly 40 years they've been unable to move past developing those two characters cinematically. DC has a great stable of fine characters (i.e. Wonder Woman, etc.,) but they've never gotten attention because WB basically doesn't know what to do with them.
The same holds true with FOX and its X-Men franchise. To date, they've proven they really don't know what to do with the comic's main marquee characters, so they just continue developing (and over-developing) Wolverine, Magneto and to a lesser extent Xavier.
It's almost as if they're terrified of telling a movie story without
those three characters dominating the storyline. So sad.