I played the Volkihar side and still got the vampire attacks (Maybe some people just got lucky?)
I don't mind them though - I've never had a dead NPC from them (Maybe I just got lucky?)
They still attack in the wilderness but they don't attack in towns, you may have been unfortunate enough to have become a Vampire at the exact time when the game was loading them up to attack a town.
That could be a reason why some people still get attacked by Vamps when they are also a Bloodsvcker.
Blotting out the sun makes the thin-blood hostile vampires attack towns so if you blot out the sun expect to be attacked no matter which side you choose.