In terms of gameplay mechanics, old school zoom aiming achieves the same thing as ADS. Is getting to press your nose against virtual firearms really that important in a game about shooting werevolves and vampires?
I blame this on the proliferation of Call of Duty over traditional scifi and fantasy shooter franchises. You can fucking ADS on an assault rifle in Halo now 
Okay but consider; actual longsword is fast, elegant, and looks awesome, and games would be much cooler if they actually incorporated elements of that in to stylized game combat.
Plus it's called "murder-bash" and it looks totally awesome so why not put it in the game?