Quote Originally Posted by Toliudar View Post
What's your source on this? As far as I can tell, there's no mechanical penalties for not drinking blood, and as undead, vampires explicitly don't need to eat. I think we may be applying fluff as if it were crunch here.
Nearly every vampire mythos feeding is a requirement, do they really have to spell it out beyond calling them predators in the MM. D&D follows the very straight forward classical vampire myths so yeah they need to feed. And as already mentioned Librus Mortis classifies which undead are diet dependent and which simply have inescapable cravings.