If you just can't stomach the thought of neutral and evil metallics, how hard is it to simply change the alignment in your campaign . . .
Exactly why there was no reason to change it in the first place. The original 1e gold dragons served a Lawful Good god and if they, as a group, aren't aligned with Good I think of any other creature that should be. So far I've seen no artistic/conceptual justification for this change, just seems to be what Derren says.