Dragons are overdone and boring. Returning races are overdone and boring. We've seen Dwemer, Falmer and dragons, now Snow Elves? Can we join the Prince and kill people? Probably not. Can we play as a Snow Elf? No. We can play as vampires. Predatory creatures who aren't the generic and pathetic benevolent stuff we always see. I don't mind seeing the Snow Prince, but as long as there is a dark plot, with dark characters and vampires. Then I'm good. No more heroic stuff. There are more things that has potential than a few white elves.
And for those of us who have no desire to play as a vampire? Any such DLC that has a vampire specific main quest would be useless.