Because they are not using her like they should from the comic story lines and are making her a weakling little girl who cries all the time because she wants the touch of another person in her life without them either being absorbed in almost their entirety, like Carol Danvers was, or end up dead or in a coma.
They cannot make her with this flight power and super strong nigh invulnerable either because it would be too hard for one without making her almost totally a digital character and because her story is kept secret from most when those who know about her know she was adopted by Mystique in disguise and she did at one time call her Mama.
She was part of the Brotherhood at that time as well until Mystique basically forced her to stay connected to Ms Marvel for as long as she did because something in Mystique told her that Rogue would keep the powers from someone if she stayed touching them longer. It really only made sense to her but Rogue was not ready for that burden and ultimately left her in search of help from Professor X.
How did that work out for her? Well not entirely well as she could have hoped but she is a great person, a compassionate woman and a badass fighting bitch so a welcome member of the team now.
