Re: I'm confused*
There could be several reason, software that otherwise should be rewritten (and heavily re-tested), parts and counterparts of mission hardware designed for, or to be connected to those rigs, and so on.
IIRC, the last Hubble service mission needed technicians to work on '80s era hardware and software, because that is what is used on Hubble - and to be sure everything worked as designed they needed to test on the real test hardware, not on a simulated one.
Biting the hand that feeds IT
