A few things:
Speaking for myself: I am most attracted to girls (and younger women) who have a combination of appreciation for their own sexiness and intellectual faculties like knowledge of and passion for literature, art, science, etc. That said, I find "plain jane" type girls perfectly attractive.
I must disagree with you about your assessment of at least Amy, the main character, much as I did by your contention years earlier that Abigail Breslin was chubby in Little Miss Sunshine. That girl had a damn beautiful face, and I can't express that loudly enough. Tell you what, old friend-if you don't like her, I'll be very honored to take her to the spring formal in your stead :)
I fully get "sexualization" vs. hypersexualization, and the distinction was well said by you. Of all the girls in the film who were part of the main crew, I felt that only the main protagonist Amy had that issue. It wasn't because of her involvement in twerking, but how she had a much stronger need to rebel than the other girls due to her very repressive Muslim family that imposed their religion on anyone born into it, and how even her mother was unhappy with it (what with her husband deciding to take a second wife, something his first wife and Amy were both very unhappy about). Youthful rebellion was prevalent in all the crew, of course, which focused on their collective need to "act out" by doing unsavory things such as stealing. However, all the girls handled the twerk dancing group better than Amy did, who took to extremes as she did for the reasons that she did.