It does seem BB is very cruel on old guys, I don't see any Kurt Thomas (39), Steve Nash(37), Ray Allen (36), Jason Kidd (38) or Grant Hill(39) standard players let alone Robert Parish (43) or Kevin Willis (44).
I think we just need to give it time. We're in season 18 so the very 1st BB draft class (before season 2) is only 35-36 years old right now. I think in 5-8 seasons there will be a lot of decent BB players in their late 30's.