Why players whining about "nowhere to spend money", but when we come with suggestion about things which have sense - thread immediately become a paper roll full of justifications "why that cannot be".
Because it doesnt fit in with the stablished lore or storyline of the engineers.
Wow, thats a really definte reply. I guess you know Prof Palin on a personal basis, and had dinner with him a couple times? If an engineer says they "require 4 wingnuts to perform the upgrade" I don't see how you can be certain that all 4 wingnuts are being used, or if they are being used at all.
I think they are more like the builder who charges for a full bag of gravel, uses half and puts the rest on the truck fir the next job where they charge again.
Every upgrade do something with internals at physical, so materials are not payment. So no.
And i said earlier - engineer not alone.
So it's fair to pay for upgrade
Maybe they use clones or slaves? Maybe they are so rich and have their own planetary base they dont need money? Maybe they charge 1 extra Mat per upgrade as they are rarer than Credits? And we do their shopping for them at our cost so they get what they need for free....or sell the Rare goods instead?
but mainly because it would just be broing to have yet another thing available for credits, the idea was to introduce different gameplay to the player that they may not try....like relogging, nobody would do that if it wasnt for engineers
Edit: maybe they are under a Criminal Proceeds Order where any credits are seized to pay back for their crimes.