I've always thought the same. And the way I've always imagined it, is through repair kits.
-If the weapon is repaired before it reaches 0 durability, it counts as maintenance and nothing happens as it is know.
-If the weapon is repaired after it reaches 0 durability, it goes down to the previous quality level.
-If the weapon was already quality 1 and reaches 0, it is completely obsolete now.
force you to a new level of awareness during combat not letting your gun break in the middle of it and a sense of I better make sure to maintain all my tools and weapons before a big fight.