To keep people buying mods instead of "old" guns being stripped, if I remember correctly.
It'd at least give Munitions people something to do, searching for unused guns, stripping them down, and reselling parts. Creating a more flexible economy than where things stand now. Even if all the mods on a gun outweighed the price of the gun itself, it still gets sold for it's "base" value (circumstances applying).
This may be working as designed, but I feel the design needs changing.
Weapon mods are as expensive as the weapon themselves fairly often, particularly once you have paid for someone to install if. Knowing I could go back and have said person uninstall it if need be would go a long way towards adding the mod in the first place.
So, on that topic, let's also immediately include the idea brought up for uninstalls at the town hall:
Uninstalls should cap at 75-80% of the installers skill, not all of it, to prevent impossible uninstalls due to skillcapped installers creating monopoly.