Yes, I think the lack of Cool Exoticness probably is the problem. All the oppression of the roma with none of the romance!

I also think there are actually quite a few (though my fantasy literature knowledge is limited) cases that could be interpreted as metaphors for Jewish groups but they are less explicit than other groups, due to less obvious physical differences between Jews and Default White Race.

Quite possibly. oliverm pointed out some in The Elenium which I hadn't noticed.