Creatures of the night are a sad joke in a game where it's always day.
Even thieves are a sad joke stealing idols and whatnot in broad daylight. Amateurs.
Baldur's Gate won't be half the city it used to be without night time ambience and thugs and courtesans on the streets.
And back to the topic, no I wouldn't like playing as a vampire or werewolf in Baldur's Gate game. It can never be done properly in a game that doesn't focus entirely on that.