Yeah I don't think it's a stupid question, it's a perfectly valid question, and one I have often wondered about myself.
A lot of the time, people of a different race may have a different cultural background which can make dating very hard on the couple and on friends/family as well.
Whenever people say things like 'oh that's a stupid question, I don't see colour blah blah blah', I automatically think 'Ooooh, you're trying so hard to not sound racist.' and it makes me laugh. They're probably not, I do realise that lol but that thought just automatically occurs to me.
I heard an Iranian/English (born in Iran, moved to England as a teenager) comedian once tell a story about how she was trying to tell her mate about a bloke over the other side of the room at a party. He was the only black man there. She was trying so hard to be politically correct, that she ended up saying, 'Oh, you know Steve! Tall guy, curly hair, blue t-shirt... Nigerian accent.' ;D That really cracked me up, because I know some people like that.
I don't believe that anyone doesn't notice colour at all, they just don't make somebody's colour mean anything to them is what they mean... if you follow me!
All that said, I have already told you about my interracial nookie experience ;D
Where I live and work is predominantly very white (apart from the Japanese, they love it over here!) and so any interracial couple is going to get a few second glances. I'm sure my friends would have something to say about it! So there are so many extraneous factors that can come into this debate. But I am a great believer of fuck everyone else if you love someone!