Irrelevant. There are ways to tell isolated stories in a manner that the established Trek backstory becomes unimportant. "Voyager" was a perfect example of this. They took a Starfleet ship and cut it off (originally) from everything we knew or cared about. They had a clean slate. They could have done anything they wanted to with it. Instead, they fell back on the same tired old concepts because they couldn't bring anything new to the table. Deep Space Nine brought a lot of new things to the Star Trek table (specifically, the ideas of J. Michael Straczynski). You can love or hate the show, but you can't deny that it tried a lot of things that had never been done on Star Trek before. The relevance of backstory is only as big or as small as you allow it to be. You can treat it as a source of ideas, and milk it to death, or you can be afraid of it and run away. The franchise has been running away from the backstory of Star Trek for years now, and the concepts of Star Trek along with it. The only thing they are truly afraid to let go of is the profitable "Star Trek" brand name.