I'm white, so obviously, there's no way I've experience in dealing with such things personally, so I only have observation and speculation to rely on </disclaimer>
I don't know the demographics in the North Hampton area, so my only familiarity with University towns in California could potentially apply, and various flavours of Asian tend to be over-represented, compared to state demographics as a whole, whilst those of African or Latino ancestry are under-represented amongst the same. I don't *think* that Jeph is deliberately white-washing the comic, but yeah, I think that your points stand, even if it's non-intentional (and for bonus points, Emily also fits the "nerdy Asian" stereotype). If the NH (no, not that one) fits better with the comic's demographic, I wouldn't have much concern, myself, since it fits the world, I don't think it'd be as bothersome. Hell, there are more robots near the main cast than non-white characters, and they have shown more development, aside from the exceptions of Tai, and Padma's brief run.
I hope that both Emily and Dale get more development, especially since Emily is close enough to Claire that she felt comfortable coming-out to her, and Marigold being close to the main cast, and both being with Dale and him working at CoD, that he'll get more development.