Not even Spielberg has the kind of power today that he can make whatever he wants if he stays under a certain budget (and Spielberg really did not want to make a 4th Indiana Jones movie and it shows).
Terry Gilliam gets to make movies, but he has only been able to make 4 in the last eleven years. John Ford used to make 4 in a year and most often they were ones he wanted to make (studio heads were happy when Ford would do a film for them as a favor).
That is really the big difference: directors in the studio system could amass enough power to make the films they wanted to make. Now directors are brought in as part of a package, and the stars are the major attraction.
One director who has been smart is Soderbergh. He makes his studio films to finance his more personal work -- in the mold of Hawks and Preminger. Nowadays directors