I will not join this debate, but here are my views on vampires:
-Vampires were created by Molag Bal, the Daedric lord of Corruption.
-Their food source is blood; human or other, they are sorta like Parasites.
-They are undead (which is particularily shunned as a form of magic), & their personal form of magic focuses on poisoning, manipulating & leeching the life-force of others.
-The process of becoming one is painful, & usually forced.
-They are unlike regular lifeforms in that they are not dependant on the sun, rather the darkness, despite their origins.
-Rather than negotiating with the daywalking species of Skyrim, major vampires such as Movarth & Harkon (I know, not the same level) would rather dominate their mortal peers, & have been shown to attack in public places, sometimes killing for their masters.
These facts do not mean that people who are vampires are necessarily bad, but their design as a species most certainly is. Perhaps their natural behaviour & negative representation by the public is what turns these creatures of the night on darker paths in the first place.