I personally hate wearing make-up and probably never will. I was chosen to get made-over on time with makeup, and I hated it. Who likes all that gunk all over their faces?
That aside, the only way I would wear make-up, is if it's to cover up a dark spot, or something like that. That's the only logical reason I could see for a person to wear it. Lipstick and junk like that, ew.
Now, the reasons people wear lipstick, is to make their lips look fuller. Eye shadow/eye-lashes, to make their eyes look bigger. Um...I don't know about the other stuff and can't even make assumptions with that.