A thought occurred to me earlier while I was watching a documentary based upon mythological vampires and how they were depicted as bloated corpses, I began to think about the depiction of Vampires in ESO and I saw some similarities between the 2 and I came to a conclusion.
Vampires in this game look the way they do because they must be based on them, they were the original depiction or one of the earliest that people remeber and the vampires in this game are of the original Vampire Clan, the vampires in ESO also look like bloated corpses at stage 4, they take no damage from sunlight and have no fangs just like these mythological vampires.
The concept of being effected by sunlight came along with Bram Stokers Dracula where he was merely weakened by Sunlight just as the Volkihar Vampires are merely weakened by sunlight, they came after Lamae's Clan and are clearly a "Dracula Style" type of Vampire, so don't complain that the vampires in this game are not true vampires because they lack fangs as the true depiction of a vampire didn't have any either and they as well literally looked dead.