Have what? There is no night system, so it's of little relevance.
Vampire [spawn} will already be playable in form of Astarion's Origin, so it is no impossible that it will become race/background, like undead was a race in D:OS2... or it might be unique to Astarion, as it doesn't seem like he has many unique mechanics tied to him.
Personally, I prefer to kill were-things and vampires. To me it's a bit like playing as a goblin or a ghul. Just not very interesting or appealing.
