I wonder if Joss thinks we're conditioned enough to start a "vampire good" arc.

I know I realised the possibility of a vampire-human détente further upthread... but another thought strikes me, that Dracula could also be used to show the limits of tolerance... that there are some evils in the world that no amount of acceptance can reconcile with, unless you fundamentally change your own values to something unrecognisable. So Dracula cooperates with Buffy, is helpful and friendly, wins our sympathy... and still enjoys snacking on Eastern European refugees, so Buffy has to stake him anyway. And also cut off his head and bury it at a crossroads with holy wafers stuffed in the mouth for good measure.