Well I think @MidYearDiary has nailed it when she said Well, I think she's right, to an extent. Popular charismatic people can get away with being babyish or plain odd in ways that people who may struggle sociallym or stand at more of an angle to the mainstream cannot. In fact, I think it says a lot for her social intelligence that she grasps this.
I totally identify with how your daughter feels about playing it safe, and her reasoning, and as has been said above "it says a lot for her social intelligence that she grasps this". When she is an adult and had her own home & hits her stride, she may well have the strength to do as she pleases.
If anything, I am in huge admiration of her self-awareness, that in order to carry things off you have to be the full package and have the outward confidence to make it work. At a time where everyone is being encouraged to express themselves however they see fit, it's refreshing to hear of someone who actually still understands the basics of how things are underpinned.
Clothes-wise, I am incredibly boring and stick to what I trust, but I wear it well and I get complimented accordingly. Even if I had the confidence to step out of my comfort zone, I wouldn't have the visible confidence or finesse to pull it off - I'd be aiming for Kate Middleton and ending up as Su Pollard.
I appreciate the two people in my next example are both males, but compare the styles of Tom Allen to Joe Lycett - they both seem to be heading in the same direction, but Tom Allen has it nailed it, where as Joe Lycett, well...