I don't agree they've kept the franchise quite fresh. They attempted to branch off with Origins. After that they delved into a period piece. Then a foreign set movie (almost unheard of in CBMs) then a Sci-Fi movie. Next they'll continue with the Sci-Fi and add some disaster movie to it.
Plenty diversified
That being said they could do with mixing up the characters
I wasnt talking about 'genre' as you see it, its still a surperhero movie with XMen team. When people say diversity, they are talking about the characters and roster. If you keep using the same team or solo hero over and over, the new factor is gone, and general audience sees it as the same thing, different plot.
Marvel is doing diversity, 3 different solo series, one huge team (Avengers) and a new team of unpopular/fresh characters. so, they have as of right now 5 different things going on.
And the audience as we know has responded pretty well.
Fox on other hand, the latest years have only done a XMen movie followed by a Wolverine one. Thats only 2 different things. Thats not diversity. Thats a limited approach. Now they will do F4 again, so that would mean 3 different proyects for the audience, but still, its the same thing they did years ago, XMen movies and F4 movies, so... its same old story.
The audience needs new blood from time to time, and thats why Marvel has had so much success these latest 6 years. They took advantage, and they won.

t: )