I don't wear makeup and my ex complained all the time that I wasn't pretty enough to not wear it. He liked girly girls and I'm a lazy tomboy. Yes it's a bit offensive but at least he's honest about it.
I think even worded nicely it's a bit rude and I'd be mad. Especially since it was a request. She probably would have gone back to her normal routine next time without anything being said. But you need to like her without makeup too or move on. No one can be made up all the time!
It really depends if she always wears makeup then that's probably her default and she'll go back to it but if your basing your attraction to her on her makeup then that's a real jerk move. everything with girls is a dangerous road to travel so be very very careful about how you word it.
I do what I want, and take his suggestion into account. I always wear mascara when I go out, so I'm never going without. If he tells me to put more make up on, I probably wouldn't, since I don't like wearing it to begin with.