This is a little interesting at least.
For the ones that do wear makeup, would you feel as comfortable, confident, or attractive if you didn't wear it? For dates, or job interviews, or work, or just going out in general? How many public photos do you have where you are not wearing makeup?
I've noticed a lot of women seem to not wear makeup much on days where they don't have much going on or days where they want to relax and aren't going to be seen by anyone. If it really was just for yourself then why do you mostly only where it when others are going to be around?