He's probably also tired of the network hierarchy and the allegiance that must be paid to network programming and movies produced by parent companies. At Fox, he would have been forced to promote everything that came out of that company's studio.
And, yes, basic cable is the new place to be. TBS, TNT, HBO and USA are producing comedies and dramas that are better than those of the old networks. Programs like "My Boys," "The Closer," "Leverage" and the dearly departed "Monk" are better than anything on CBS, NBC and ABC, with few exceptions.