I guess people don't remember when Ron Moore talked about how restrictive the Trek canon became when trying to establish backstories during the later seasons of TNG and DS9. When you have this massive pile of canon to deal with, setting something post-Voyager is going to encounter much of the same problems as a prequel series. As others have said, the best way do Trek is to start over completely - no divergent universe created by a villain, but a complete clean slate, like what JMS' abandoned series concept proposed. There is so much previously-established conventions and history, the shows become almost impenetrable unless you know the entirety of the backstory.
