It puts us at a disadvantage in a lot of ways. We spend more on making ourselves more attractive because if we don't we're likely to make much less money in the first place. We don't have a choice about whether we send out signals with our dress, so we have to always consider what message we want to send when we get dressed in the morning. There's also the health problems that result from more extreme measures of attaining attractiveness, from botched plastic surgery to eating disorders to sprained ankles from high heels.
I hear some guys complain about the portrayal of men on some sitcoms as bumbling fools, but, hey, at least fat, unattractive actors get work with relative ease. There are almost no women in the media who are just *moderately* attractive. They all have to be way above average.
There's the entitlement this whole business breeds in some men, too. They start believing that it is the job of a woman to look good for him. So then you get all the fun comments like "hey, you're too thin, men like a little meat on the bones" and "don't cut your hair short, guys will be put off if you look too masculine" and "don't dress too sexy or we'll be forced to harass you in public" and "don't dress too conservatively or you will look like a frigid prude."
Oh yeah, and we end up with millions of women and girls who genuinely believe that their looks are the most important part of them. That being pretty is much more important than health or education or, well, anything.
It's massively dysfunctional and an all-around pain in the ass.