Well what I mean is that if its a full blown Abbey, having the ability to go in there, blow it up or shoot it up might be a bit controversial, and thus Bethesda might try and avoid tackling it. That's the only reason I could see not making it a DLC feature.
Depends on how its handled I guess. I may just be making something out of nothing though.
Do we really need another zealot faction?
If you want inquisitions. The Brotherhood is right over there in the Commonwealth. Do you think the Followers of the Apocalypse have no point as well? Not every faction needs to exists to burn and pillage.