There are alot of younger GB memebers now, and with that I think it's possible that many of them just plain don't know anymore history than what's in the Proclaimers book. There has to be a few that kinda have an idea what happened when ones were removed in the 70s, but do they REALLY know what's in the old literature? Or what really happened during Rutherford's hostile takeover? Or stumbled upon some old packets of miracle wheat? Is it possible that many of them are just ignorant?
Theory about all the warnings about apostate material
Bethel has one of the most extensive libraries of WT publications and most of it is open to reading by Bethelites. Just because some of the older GB have died does not mean that jws from the same age bracket are not still alive (at Bethel as well) and remember the good old days and share it.
I don't know if we can even generalize among the seven GB members. There are probably a couple sociopathic liars, a few compulsive liars, and a couple who are genuinely ignorant/deluded making up the body.
That said, I think it is important to remember that the GB has very little to do with what JWs hear at meetings/assemblies and read in the literature. Everything is farmed out to committees and filtered through a bureaucratic hierarchy. It is quite likely that the GB only has minimal input into the operation. They're more of a puppet or figurehead at this point.