It's the way DC has always been--very editorially-controlled. You can look at the editors as being the ones in charge in the way a producer is in charge of a TV show, and the writer is perhaps only slightly better off in comics in this situation than in TV, but only because of greater fan identification with them as perceived creators than is the case in TV.
This isn't just the case at DC proper either. I know two Vertigo contributors who will remain nameless who have told me of some of the most foolish editorial interferences in supposedly creator-owned books. But then, they're not really creator-owned as long as the reversion clauses exist in the contracts.