I don't understand the angst and disgruntledness for two reasons:
1: Different stories.
2: Different writers.
...and as such different 'agency'. She was front and centre in one, she's not in the other...what's the bigfrakkin'deal? Characters get rotated in and out of prominence all the time depending on who the writer chooses to drive the story, at the time and the type of story they want to tell.
Character-specific fans (of all characters, not just Jean) need to either:
Seek therapy to come to terms with the situation (because unless they start writing for Marvel's X-Men, it won't change and all that bitching and whining can't be healthy).
Take a sabatical when their favourite is not featured. (Jean is featured front and centre in X-Force, yay!!!)
or...and this might be revolutionary to some:
Learn. To. Love. And. Appreciate. More. Than. One. Character. Or better yet...The. X-Men. As. A. Whole.