Because, of course, if you were doing that, you would put one of your most popular writers, Brian Bendis, overseeing the X-title (and solid art and writing talent across the line).
There's no question that Marvel's been promoting the hell out of the Guardians of the Galaxy leading up to the movie. But I don't see any more focus on Avengers (and the components thereof) than the X-folk. The Fantastic Four are something of a mess, but that's more the current regime than something that's been a long-term strategy I've seen. Similarly, it's not like Spider-Man hasn't been a major component of Marvel's output, either.
I'd say that Marvel will in fact do stuff (including merchandising deals) that net them the most money, but they also (to the extent the comics still matter in the overall Disneyverse) recognize the whole creative portfolio is of value. So the X-Men, Spider-Man and the Fantastic Four will still be flagship franchises, but expect that any title tied to an upcoming movie will get some extra (and understandable) love.
Reshared post from +Alisande Morales
Interesting take, what do you think?
Why Marvel wants the X-Men to fail
Is Marvel actively trying to downplay the X-Men? It would actually make a lot of sense for the company.