Li Shenron
Legend
The hook for the aasimar is about the same as the tiefling, except from the opposite direction - everyone expects them to DO something (good somethings).
That's a viable story hook for a character, under certain circumstances, but it's not intrinsic to playing the race. This is D&D; your PC's not going to be a non-adventuring stamp collector--or if he is, it's a one-time hurdle that will be dealt with once he's dragged into the campaign.
If I were travelling/working/adventuring with someone who is partly an angel, rather than expecting them to do something, I would expect them to tell me what's right or wrong.
The problem eventually is that the player doesn't probably know that.