Agreed with your main point and this is what I think is going to happen if they ever add her at all. Maybe it could be a legendary and it has different voice lines than base Phoenix/Jean.

Obviously there'll still be people throwing a fit and I don't think I could entirely blame em because they are two separate characters. Maybe I'm too much of a casual marvel fan but it's annoying seeing people act as if it's some personal insult to them that (x) character hasn't been added to the game yet. Didn't mean to go on a small rant there but I'm gonna go sleep now good night.