Seems to me that the SR9 series was a move away from
a military-style rifle toward a target one- a move to
please politicians. The lack of a flash suppressor is part of th reason they weren't that well accepted but also the
thumbhole (for only the SR9, not the T or TC) stock.
Generally, that type of stock was and still is a hated
BTW, some of the very early HK semiautos are much rarer than
the SR9 rifles.