Not marrying/dating someone is different from depriving them of rights, or seeing them as a lesser person. Who you choose to date, and even more-so to marry is a very personal decision, and no one has the right to judge you on it ethically in my opinion. There are thousands of fish in the sea, but there is only one person you'll choose as your mate. Alternatively, I'd say I'd hire or befriend anyone equally-- living in Japan, my best friend here is an African American, and my best friend from highschool is white. but talking marriage is talking about becoming family; becoming blood. It's a completely different thing...
In the case of marriage especially, cultural backgrounds and cultural heritages, as well as religious ones play BIG roles in two people's compatibility-- and even bigger roles in their ability to make a good household together. Especially for people who feel strongly about their cultural or religious associated beliefs, choosing a person with starkly different or opposing beliefs is probably not a good idea.
For myself, I've dated a lot of different women from a lot of different backgrounds, but at the end of the day, I'm very doubtful I'd be able to marry someone who wasn't asian, and probably unlikely to marry someone who wasn't Chinese or Japanese (I'm half-half). My current girlfriend strongly feels the same way.
It's funny, as I'm amongst the 4th generation born in America (my GREAT GRAND PARENTS were from Japan/China)-- and yet despite that long immersion into the US, while my mother was amongst 4 siblings, all my cousins are pure Japanese (ie. their parents all married Japanese-Japanese), and even my mother married Chinese, still east-asian. Amongst my 8 cousins, the majority of past boyfriends/girlfriends have been Japanese (or at least asian), and judging by how things are going now...
My oldest cousin married a Japanese national, and his younger sister recently got engaged to another Japanese American. My younger cousins'/sibling's current/recent boyfriends and girlfriends (and my current girlfriend)-- all Japanese or American Japanese.
While I think of my family as being very Americanized, open minded and modern, it seems preference in choosing a mate runs very deep on a different field of thinking from philosophy or logic.
I don't think there's anything wrong with that. All's fair in love and war.
edit: Also I DEFINITELY know that I've been shot down numerous times picking up white girls for being an asian guy. If you are an asian guy living on the mainland US... sucks to be you bro. Racist bitches (lol@ hypocrisy)