Unfortunately this movie entered with the arrogant notion that everybody would just know who everyone was and what they did, and the only characters they really explained were those that they created for the movie. Don't get me wrong, I don't dismiss the idea of a comic book film made just for the fans, but in this case I would say that while that may have been the intent it fell greatly short of the objective. While as a huge Wolverine fan their were many moments that I ooed and awed about, their were so many plot holes and just plain lack of information that as someone who has read every piece of Wolverine literature I can get my hands on...I was just left wanting.
In the specific case of Gambit their were many issues, and much of it in my opinion stems from the Actor. I have met Taylor Kitch in person as I worked with him on the TV series Friday Night Lights here in Austin, and from the way he talks I can tell you that he didn't ever seems to be any real comic book fan. That's nothing against him personally, you like what you like and you don't what you don't, but in his case their never seemed to be any passion when discussing Gambit, and when asked about other characters he never seemed to have anything to go on. As an actor he is...okay, but as you saw in Wolverine he can't hold much of an accent. In fact it took him a while to grasp the simple Texan accent used for Friday night Lights, and to be honest I didn't see a bit of difference between the two. Most actors, most not all, who take on the role of a comic book character seem to get really excited about the literature behind that character and bring their desires for what they would like to see from that character to the Director and to the film. As Taylor never appeared to be concerned with much aside from his paycheck...and the ability to "Really hit people on set", it doesn't surprise me that the character had a lack luster transition on film.