In my opinion, these two factions are so focused on the past that they are unwilling to create a better future.
The thought began to occur once I was reading through the entries in this wiki.
It's kind of tragic really, because both these organizations kind of started with good intentions at heart you know.
Enclave wanted to restore the country and the Brotherhood of Steel wanted to prevent technology from falling into the wrong and incapable hands. But they kind of lost their noble intentions to a struggle of dominance.
I actually feel bad for these guys that they are so living in the past that they are unwilling to work with rising powers like the NCR to build a better future.
It seems that the only right way to do it is like how the Followers of The Apocalypse try to.
I basically agree bt you are only talking about BoS West Coast, right? So, let's leave Capital Wasteland Chapter out of this :)
Enclave had a noble goal but in practice, they abused that goal and used it as an excuse for their greed of power, their self-righteousness led them into an evil path, they looked down on everyone, refused to bend in the new world, but don't forget they are the descendent of shadowy pre-war American elitists and industrial-military complex, which was already evil and arrogant at first place.
Brotherhood of Steel as a post-apocalyptic knightly order is naturally closed to outsiders, as a direct decadent of U.S. Army, they had every right to prevent sensitive technology from falling into wrong hand. But overtime, they become more and more paranoid because of overwhelming stress of post-apocalypse, fear replaced courage, now they only hide in the stinky holes.