I think the problem is that Bethesda can't help themselves from making concrete lore decisions without thinking about the implications for both the previous titles or future titles.
From what I gather there is no real process at Bethesda for lore additions. They simply pitch a quest, if it sounds cool they make it. Lore does not even really enter the equation. They used to have a lore guy but he was fired around the Oblivion time so since then they have been doing everything freestyle.
When it even occurs to them that they're violating established lore, they spend about 5 seconds coming up with an ad hoc solution. "It doesn't make any sense for the Brotherhood of Steel to be in West Virginia 25 years after the Great War? OK, how about if some woman there was a friend of Roger Maxson and established her own chapter, then it got completely destroyed by
draegons scorch beasts? Then the west coast Brotherhood sent another team out to investigate." It's still completely fucking retarded, but it gives fuel to the shills and morons who defend Bethesda games online. "Ackshually this isn't terrible writing. It was explained in a holotape that you clearly didn't listen to."