You have a point, Chimp, and maybe it comes with the definition of "monster".
I personally wouldn't consider a Dragon a monster. There are many many examples of dragons getting on with human kind, as well as others whereby they are after eating buxum, beautiful, virgins for breakfast. This comes down to the personal preference of the Dragon in question. And therefore there are "good" and "bad" dragons as there are "good" and "bad" people.
However, the likes of Vampires specifically wish to drink human blood with one of two effects, death for the victim, or turning the victim into another vampire. Under these circumstances, although rat blood or cow blood will do, vampires have a prediliction for human blood and will ultimately try and get it!!
Zombies one could see as being akin to a virulent disease like ebola,a nd wouldn't we want to eradicate ebola?
Therefore I suppose it comes down to one's definition of "monster", and the ultimate raison d'etre, of the "monster".
Definately some consideration required on my part!!!