Not that I think those guys are bad coaches, but sports in general has this,thing about hiring retread instead of giving a younger guy a chance, and thus we end up with a Paul Pasquoloni, when you possibly could find yourself a Kevin Ollie.
PG's do make good coaches like Ollie
Doc Rivers
Lenny Wilkens
Mark Jackson
Cousy (he made BCU respectable)
George Blaney was an NBA PG