If the creators of Vampire lore knew that leeches used an anticoagulant and a long siphon to drink blood, or that a vampire bat nipped a sleeping victim and lapped the blood, the legend of vampires would not include sucking...but that said...
I am pretty sure that whoever created Vampire: the Masquerade, borrowed heavily, especially the idea of the flesh shaping Zemichi(forget the spelling, but pronounced Zahmeechie, as opposed to Zamahchey...and the same people who pronounce it that way call the Ventrue, Vontru....and probably call the chain store Target, Tarjay.) Well, they got the flesh shaping idea from Brian Lumley's Necroscope books...mainly the stories about the Nightside/Sunside Vampire world. Shaitan was the first vampire, but the coolest was probably Vormulac.
George RR Martin's Fevre Dream is worth reading...for all you not sick of the vampire/zombie meme which is all about the impending boring and craptastic apocalypse world, where we dehumanize anyone outside our own family or other social group that also wants to eat.....so we can headshot them without any slight to our conscience.