You can't call it "Wolverine: X-Men Origins" because then the movie will no longer appear in alphabetical order next to the other movies when it's on a shelf at a store. This is why "Raiders of the Lost Ark" was changed to "Indiana Jones and the Raiders of the Lost Ark".
That's a good point and an interesting take on the question. Although W is right next to X in the alphabet, so it doesn't make too great a difference in that case...
In the mid-1980s, when the tv show that ultimately became Star Trek: The Next Generation was being planned, someone at one stage suggested just calling it 'Star Trek' and again, letting the viewer figure out which version it was. Obviously, that idea was nixed, though the idea wasn't entirely without precedent.
Conversely, the makers of DS9 considered airing it without the Star Trek supertitle. And Enterprise didn't add Star Trek to its title until, what was it, the early 3rd season? They tried going without it, but it didn't work out.
And I'm still bugged that the new film is just called Star Trek without anything to differentiate it.
IIRC, the revived Mission Impossible tv series didn't have any 'Next Gen' or '1980' type tag to it.
That might be because it was originally meant as a remake rather than a sequel. It was commissioned during the '88 writers' strike and was going to be simply reshoots of original scripts. Initially, they were even going to use the same character names and simply recast all the roles. When they decided to bring Peter Graves back as Phelps, they changed the other characters' names and made it a continuation, and the strike was wrapped up soon enough that only the first four episodes were reshoots of old scripts.