Precisely which secondary lines would BNSF like to have back? Do you have a private line into the inner sanctum? If they were worth anything, another railroad is running them still, which BNSF could buy out if it wanted to (or let them keep running things with BNSF running overhead trains). If they were not worth anything to anybody then, it's hardly likely that they are now. "Everybody was doing it" is hardly an excuse, but there was a reason at the time for it to be happening.

Note that one "secondary" line *was* saved, because there was some future use potential, and was eventually reactivated: Stampede Pass. The disposals weren't done without thought.