Given that our 20th/21st Century technology has grown by leaps and bounds since this gaming system and fluff were created, would not most dropships/jumpships/warships/space assets and planet bound bases have 3-D printers for making repairs?
Insofar as retired 'mech designs, after productions halts and the remaining units relegated to second-line units, once those individual units were heavily damaged for the umpteenth time, as in THX-1138, I can see where some actuarial ran the paperwork up the chain to scrap those 'mechs. The 'mech comes in, Cooter winces as he checks out the damage. He mumbles something like 'poor old girl', because due to orders, he must strip it down. Any remaining weapons are pulled out along with other components and added to stockpiles. The remaining framework and armor would be removed, sorted, and sent to the smelters to be recycled.
Working in government, I have seen similar retirements of equipment and software. As long as the 'leader' is full of themselves, functionaries can ram all kinds of poor decisions through the system.