Hmm, in general I agree that durability as it is now doesn't really serve a purpose. We can look at this from multiple angles. For DOSII I think game mechanics, strategic / tactical depth and thematic / narrative purpose are of importance, and I'll discuss these points of the current system. At the end my suggestion.
For game mechanics, it enhances item interaction with the player. A new 'statistic' of an item. However, at the moment this boils down to 'carry repair equipment and watch out for the yellow UI'. To me and I think most players, the resulting interaction with items (repairing = clicking the item and waiting, or even worse, going back to town to repair) is pretty dull.
At the moment, there is very little you have to think about strategically or tactically. Again, just make sure you have repair tools and watch for the yellow icon. Most scenarios where you broke something (you forgot tools or you didn't know), are not fun. It doesn't make the player feel like they made a bad choice, it's just like forgetting real world stuff.
Now thematically it makes a lot of sense. It gives the items more personality and story development (however limited). But I think that a counter going from 60/60 to 20/60 to 0/60 is, again, pretty boring.
Your suggestion definitely adds (in my opinion) some possibilities for tactical decisions. For example, a skill that can break or damage equipment. But what would happen if you have a 2H knight, and his weapon breaks mid-fight? Is he going to fight with fists? I'd imagine the damage reduction would be really bad.
The question is, what are we trying to add to the game here? I think thematically, it would be fine if there would be no durabilty, but you find 'broken' gear (trash items), similar to gold plates or cups which are currently found in worms and crocodiles. To give items more personality, I think upgrading or enchanting them at a blacksmith would be better. Or maybe the items can gain bonusses from certain activites. If your character walks on fire a lot, boots could get additional fire resistance. It's not realistic, but it doesn't have to be. Getting or investing in gear for bonusses adds more decisions Use your old gear, now upgraded, or use newer gear that has more upgrade potential? Maybe NPC's could demand 'personalized' old gear in case of a robbery, or newer gear? Maybe items don't break, but lose monetary value over time?
