I have often felt like the only person in fandom who likes her! I think it's a little of both the things you suspect, plus in that S1 Rolling Stone article, she apparently came off unlikeable? (Which, per an interview shortly after in a local--Vancouver--entertainment rag, was largely because the interviewer was insanely skeevy and freaking her out. She just seemed so young and bewildered in the Vancouver article that I've always wanted her to do well since I read it.)

I think that if she'd got her start on a Whedon show, her talents would have been nourished and grown (for all the issues I have with Whedon, that's one thing he's done well by with his actors--see Summer Glau) and fandom would love her. Instead, she got screwed and stifled by M&G and company.