Personally, I think it delineates the characters who are more refined when it comes to physical beauty. The sorts that are so naturally attractive that you'd actually believe they wore make-up.
Kagome to me has always been the type who is completely average. She's still very pretty, but at the same time she's the regular school girl next door. Hence no eyeshadow

On the other hand, I'm glad Takahashi stopped at eyeshadow for Sesshoumaru... I don't want to imagine him with lipstick
On the same vein, Sesshoumaru, more or less attractive with lipstick?