Why DO girls wear so much make-up?

I've seen this floating around facebook and twitter. Most of you ladies are sharing this as if there is an obvious answer to the question. However, the funny thing is, I find this as a useful question some of us ladies should take to a deeper level.

Why DO girls wear so much make-up, anyway?

Like I've mentioned in previous posts, it seems women are always under pressure to appear attractive and hide their facial flaws. Unlike men, who are expected to grin-and-bear-it and get on with life.

While this is not a question that most men might care about, I think we who feel the pressure of embracing femininity and being women need to consider why we really do these things. Why is it that many of us have just accepted the idea of this "meme" as fact, instead of questioning the very essence of it?