Aasimar get a short stick from just about everyone. They get screwed as PCs by the Level Adjustment rules, and they get no respect from players. Frankly, Celestials just don't have a lot of dramatic tension most of the time. Sure you can have the occasional "Legacy" scenario where you couldn't possibly live up to your awesome ancestors, but generally when it's important that someone has powerful family members it's so that you can introduce evil family members, not additional heroes.