Well I'm voting up not because of "Sexiness" - and she's got that potential - and now that she's at least not jailbait age - but I agree, thinking of her as a "Sexy" actress feels wrong.
Gotta give some mad props to the writers AND her own acting. I mean think about all the other "Teen" dramas where the female characters are almost trying their best to be thought of as "Sexy" and objects of desire and lust - even though they are clearly clearly underage. But she's created a persona that in many ways akin to Nathan Fillion's own - the funny, sometimes silly, but not over the top comedic, attractive but maybe not "sexy" in that they're basically walking around with a sign that says "F--k me! I'm hot!"
We could certainly do with more actresses like Molly Quinn. She plays a good kid. Not a brat. Not a slut. Not an overly snarky, rude, crude teen. Just a good, solid, almost normal kid. Which oddly enough seems to be very rare. I mean think about it, she's the age and has acted at the age of most of the "Disney stars" that are all looks and really no brain and so forced when it comes to their acting style. She's not forced. I've never seen anything she's done that seemed "forced", even last week when she was sort of "hating" Beckett, still shows she's still capable of being a typical "moody" teen but eventually expressed why. Which not all can. If this was any other show they would have had her plotting Kate's breakup with Castle. So really it's a good combination of good writing and a good actress who makes it look effortless.
I could see her going pretty far - and I really hope that now that she's 19 she won't feel the need to "push the envelope, because I can!" I mean look at Stana Katic's characters, I don't think she's done a really overtly blatant "Sexy because I can" character. Sure she was a "Bond babe" in QofS and even the "Sexy" Stuff she does is pretty low key compared to others that can't wait to do their first nude sex scene. I don't see Molly doing that.
At least I hope not. We need more Molly Quinns... and less Lindsay Lohan's