Why is Gambit such a no go Zone?. . Is it so they can establish Rogue as a go to Gal with out him attached to her at the hip?
Its a long story, thats come to this. Gambit's popularity peaked in the 90s, which made him a top 5 or even 3 X-Man. He was even leading for a small time. Even after he peaked, he was still very popular. His appeal lasted after a couple of overzealous writers/editors tried to kill him off permanently. His use began to dwindle after the first X-Men movie. He was included in it. Marvel, not having their own studio at the time and not owned by Disney, decided to heavily feature the movie characters; Cyclops, Jean, Storm, Rogue, Colossus (even tried to pair the latter two at one point). Costumes and appearances were tweaked to mirror the movies. Those like Psylocke, Cable and yes, Gambit got put on the back burner. What didnt help was the fact that the next couple of writers werent Gambit fans, or just didnt have plans to use him. Some claim they didnt find him interesting, others were just so disgusted with the 90s, most characters that were created during the time werent given a fair shake. Psylocke, though an 80's character was most popular in the 90s, she was resurrected and brought back into the lime light due to being included in Remender's Uncanny X-Force. From that point she was almost an edict to be everywhere X-Men related. Cable stayed out of limbo due to being paired with Deadpool, however he fell into that pit eventually. Gambit became a carry-on bag for Rogue all the way up to Blood of Apocalypse. Once that train wreck was done, he was exiled into Limbo until he popped back up in Messiah Complex.
He stumbled around the X-books for a while, then got a solo and rejuvenation project to being him back up to speed. A couple writers requested to use Gambit and his new status qou but were blocked by Carey because he wanted use him to boost sales on his books, I assume (putting him on covers of books he had nothing to do with, pushing the idea of triangle between him, Rogue and Magneto), though he did use him AoX fairly well. So he went utilized for another year or so until his solo ended. He was then moved to be X-Factor as the lead character. That was short lived as it became somewhat obvious that the book was shifting gears and focusing more on Quicksilver. Most attribute this to Marvel's sudden need to push the X-Men line to the side to focus more on Avengers characters, ie, the ones they exclusively control. The book got cancelled and the creative team moved to a Spiderman book that basically sprang out of X-Factor. With no where to go Gambit has been seen in a handful of Secret Wars books, mostly dying. Many also attribute this to the fact that his solo movie had started to build momentum. No expects Marvel to give shine to a character with a movie on the horizon. Though Deadpool is getting a new book and team roster spot (he was killed off around the same time they announced his movie). But Deadpool sells books. I never thought they'd kill him for long. But for that redeeming move by Marvel, they also killed off theyre biggest bread winner in the X-Men, Wolverine (pretty close to Days of Future Past, and before X-Men Apocalypse or his next solo movie), only to bring him back incredibly changed. The codename "Wolverine" belongs to a woman now and Logan is extremely old, hence they call him "Old Man Logan".
So to summarize Gambit is a not go because;
X-Men are seemingly being marginalized as a whole (theory)
Marvel doesnt help promote Fox movie properties (theory)
Current X-Men Writers arent interested in using him/ Marvel wont allow the writers that do want to use him, use him
Past X-Men writers ignored him for so long, younger readers barely understand him