I actually like that the % is the same for all items. It makes the poor and gold items more similar to each other.
If it wasn't for this % loss, gold items would have double the durability of poor ones, which is too much of a difference. Instead, gold items tend to live more since they suffer a lot less from day to day usage degradation, but have the same durability loss on death. This in my opinion is the right amount of difference between the two qualities.
I would agree if increased quality did anything beyond improving the durability, but it doesn't. In the current system you are actually punished more for getting k/o or dying while wearing Exceptional gear than wearing Poor.
For example: (purely making up numbers) Lets say that for every hour of gameplay you take 30 points of durability loss from being hit or using your items. This number is the same no matter the quality of gear.
If you are wearing Poor quality gear (say 300 base durability), every time you get knocked out causes you 15 durability loss. In other words, being knocked down gives you a 30 minute "durability penalty."
If you are wearing Exceptional quality gear (300 base, 600 max durability), every time you get knocked out causes you 30 durability loss. In other words, being knocked down gives you a 60 minute "durability penalty."
If you want to argue that quality is giving too much of a bonus to durability that is fine and can be addressed by lowering the durability bonus from quality to something less than 25% per level. You can even argue that people should be taking more durability loss from being hit or using items. However, the current % loss on K/O and death is illogical, backwards, and literally more punishing for using better items.
Edit: I'm not suggesting that higher quality items are not better than lower quality items. I'm stating the fact that being K/O or dying is a bigger punishment for people wearing higher quality items.
If durability bonuses were reduced to 10/20/30/40 I would be fine with K/O inflicting fixed durability damage (around 25).
If we also want to express our ideal changes, I would then change the durability loss from the current system which is a chance on every hit you receive, to being a chance for every 10 damage (after mitigation) suffered.
Same for weapons, they should degrade based on the damage they inflict.
This way slow and fast weapons would degrade at around the same rate, and getting hit by powerful and slow attacks would be the same as being hit by fast and weak attacks.
But I understand that this would require dev time, and is not honestly worth it.