Where the hate comes from is the nature of the internet. The most miserable voices are the loudest, anything that is not the best is the worst, and every character is boiled down to their worst moments, usually with any context ignored.
Gambit is a sad ripoff of better characters who went out of style long ago, Logan is a hypocritical murderhobo, and a sexual harasser to boot, Jean is a harlot who is leading on multiple men, Emma is an flat out evil homewrecking bitch who is solely responsible for the Dark Phoenix (Wyngarde? Never heard of him!), and Scott, well he is a bigger philanderer than that Bond person, dropping wives at the drop of a hat for no good reason (again leaving out context such as Scott and Maddie displaying incompatible moralities when Loki was offering a false paradise for the lives of ALL the magic heroes - hardly a recipe for a lasting relationship). Again, it's the internet.