Okay, lets see. The BoS in Fallout 4 is the second dumbest faction in Fallout 4. The main reason being that they want to destroy The Institute. Now the Brotherhood I know from Fallout 1, 2 and New Vegas would never do something like this. Destroy The Institute, the most technology advanced place in the known wasteland? HELL NO! Preserve The Institute and hoard its tech, especially their weapons tech, for themselves? YES! Elijah from New Vegas would have a stroke if he saw what the East Coast Brotherhood was trying to do to The Institute but hey whatever helps you sleep at night bub.
Ah, okay, it's good to know that you haven't played the game due to your severe lack of understanding for this faction in question.
From the very first moment you meet Danse, you are introduced to the overarching idea of the Brotherhood: Technology needs to be controlled, lest it destroys man, as it did. To quote Maxson and Danse respectively:
"Look at the scorched earth and the bones that litter the wasteland. Millions... perhaps even billions, died because science outpaced man's restraint. They called it a "new frontier" and "pushing the envelope," completely disregarding the repercussions"
"Before the Great War, science and technology became more of a burden than a benefit. The atom bomb, bio-engineered plagues and FEV are clear examples of the horrors that technological advancement had wrought. We're here to make sure that never happens again."
More here. But basically, you fail to understand that the Brotherhood are not tech hoarders like before, and the notion that they have to be plays of your lack of understanding of them as a faction. Maxson redefined the ideals of the Brotherhood, eliminating hoarding and effective worshiping of technology. Collection and preservation of technology is a tool now, not a means to an end.
You don't understand the Brotherhood, at all. To once again bring up that Talus quote I posted earlier: "Wear our Power Armor as a symbol of hope as you walk the wasteland, for someday when the world is ready we will surface and restore our battered Earth." And here is one from our beloved Veronica: "Once upon a time [our purpose] was about technology. Controlling it so it couldn't destroy us again."
Destroying the Institute is a decisive act that seems confusing at first (after all, can't all that tech be used to their benefit?) so I can understand your confusion, except Maxson knows that this technology is powerful - and that kind of power corrupts beyond all measure. How long until he'd compromise the Brotherhood's ideals and start fielding synths, to preserve the Brotherhood's manpower? How long until they start copying members' minds into synths, like with Nick, to ensure they survive? And bit by bit, they become the very entity they despise. Maxson knows that, because the Brotherhood has gone down this path before, degenerating from an isolationist, but fundamentally well-intentioned group, to another raider tribe, except with fancier guns.
Whatever's lost is mere chump change compared to what was gained and preserved: The soul of the Brotherhood and humanity.
The Brotherhood of Steel in
Fallout 4 are
PERFECT.