That's one of the reasons I'm always a bit boggled by people who devour 'misery memoirs' of the 'Please Daddy, No!' variety and consider themselves superior to those of us who'd rather read Shaun Hutson or American Psycho. Do you really think it's better to wallow in a real person's anguish than lose yourself in a made-up story?
(You could, of course, run away and read the magnificent My Godawful Life: Abandoned, Betrayed, Stuck To The Window, of course.)
But I surprised myself by having bit of an instantaneous 'Eww!' on discovering that there's an actual booksellers' and publishers' category called Interracial Romance. Of course, all romantic and erotic fiction contains a fair bit of objectifying, but then so does fiction in general. And I certainly see no reason why an author shouldn't create characters outside his/her own ethnic group: if we didn't, then our stories would often be very one-dimensional (as a lot of hack genre fiction is anyway)
I think it's the concept of the label that unnerves me, really. I'm already a bit unthrilled with the way erotica and erotic romance seem to be going for division into narrower and narrower categories, with fewer opportunities for people to write a story with a mix of characters, different connections between them and assorted motivations for the erotic action. We don't all want to read erotica that's just about Someone Like Us getting off with Someone We Might Find Sexy - as is demonstrated by the biggest growth area in erotic romance at the moment: gay male interactions written by and for women.
I appreciate that readers want and need some sort of genre-indicator. If you don't like stuff that's unrealistic, you want prior warning that the book with the tempting cover actually has scenes of magic and elf abuse as well as snogging and shagging; if you are deeply vanilla you like to know how far any 'kinky' stuff is going to go. But I suppose the thing I find the most offputting about the concept is the realisation that it's actually such a big deal to some people that characters in an erotic romance are from different ethnic groups - so big a deal that the fact they are from different ethnic groups is the whole story.