Hm, sorry, what hegemony are you talking about?
I always wonder why people who go all excited about gender issues can't accept that women are not men and do not have to be like men? Your 'hegemony' (I assume you speak the well known thesis about male-dominated society) may not actually exist, and the 5 year old's desire to look attractive may not be bad at at all.
Imagine, there are two dimentions to the world. One is manifesting itself in social power structures, money, status, smart jobs, Nobel awards etc.
The other is completely different and involves sense of belonging, security, plans about rising children and actual time to spend with children, emotional connection with friends, caring, feeling etc.
It just could be that most of women are not interested in the masculine dimension of this life. Heck, I dare say they may not even be particularly fit for the struggle/rat race due to their biology, exceptions notwithstanding. But they are powerful masters of another, parallel universe, which is always here with us, and where majority of men just not quite make it.
I think of many girls/women I've known in life who absolutely hate to spend their precious time on stupid things like going to work, making sure your last project is a success, competing, 'achieving' in the eyes of others etc. This distracts them from their sacred passion in life -- that is to rise a child, to shape the child's mind and soul and to protect him/her. And protection means having a secure, clean and comfortable house. And yes, that means having a strong competitive man next the them who would provide for all of that. Basically, that means a family.
(The idea of the family seems to have been discredited both by the idiotic religious right and no less idiotic crusading left, but a strong family has a clear evolutionary biological advantage. It ensures the partners reproduce and their children get competitive advantage while growing in a happy/secure place. On the other hand, a lone over-achiever may as well become the richest man in the cemetery).
A young girl is conditioned to think about her looks because this will help her later to chose her mate and to create her family. And yes, she will be chosen for the large part because of their biological traits (beauty). And that's not a bit shameful or reproachable.
Thankfully, beauty is not the only criteria, so chill, you gender activists and spare me the flaming. Of course not only looks matter in life, and child beauty contests are a horrible thing. But still, it is normal for the girls to try to look beautiful, just as it is normal for the boys to try to be strong.