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 
I'm indifferent to iron sights but I don't think they're necessary at all if you're not going for extreme realism (or modern warfare gunwank). It's silly to me that some people are counting lack of ADS as a flaw that needs to be fixed
If a weapon has ironsights in a game you should be able to use them. Simple as.