Why? He was working for the studio. If you want to hate anyone, hate the studio executives who micromanaged every aspect of the production. Ratner, like most Hollywood directors, is just a hired gun. He doesn't even ask for final cut. He makes the movies the studios want to release.
If you think these studios are giving guys like Ratner, McG, Renny Harlin, P "Dubs" Anderson and Shyamalan $100 million to go off and make personal projects with complete creative control and final cut, then you're deluded. Every creative decision is dictated by the studio. The director's job is to realize those decisions.

He 5b4basically undid everything Ratner did with X-Men 3. I posted a thread earlier about how DoFP could pretty much replace X3 entirely. All of Ratner's work was for nothing. Poor baby.

Bryan Singer gave him a big middle finger with Days of Future Past.
http://tinyurl.com/nnmrw25

Hahaha amazing! I second that!