If I didn't attend a conservative church I would absolutely wear makeup. Why? Because I'm a girly-girl, and I love beautiful, feminine, girly things. I love everything about looking feminine..... curling my hair, high-heel shoes (and all sorts of other shoes), beautiful clothes, cute purses. To me, makeup is just part of that package.
I'm not arguing with YOU about the 'like God made me' thing... you're entitled to your convictions and opinions. But I disagree with it. When I curl my stick-straight hair, I'm changing the way God made me. Same goes for shaving my legs, and shaping my nails. As for aging.... we're part of a dying world, and aging is part of it. It's part of the decay of this world. As part of the aging process, our eyesight starts dimming, we can start losing our hearing, our teeth start rotting and falling out... yet no one says that we just have to accept how God made us. We get glasses, hearing aids, and fix our teeth or get new ones.
Makeup is not intended to change how God made you anyway, just enhance it. Just like having a nice hairstyle.
Some people have very red, splotchy skin. A thin coat of foundation can even out the skin tone. Why is that a sin?

I believe we give glory to God by looking our best.
Same thing about jewelry. It's beautiful, I love beautiful things. The Bible says that God would shower his bride with jewels.
Those are my reasons.