Ok, in short it would be a major benefit to the CM, pvp, pve, game longevity due to increased difficulty from removal of gear bias and increase the purpose of life skills. If all items lost max durability every time you repaired them, then the AP and DP gap between mid and high lvl characters would close over time because of wear and tear / attrition of gear.

This would make the game much less gear dependent and much more skill dependent

Im not saying destroy items, I'm asking why on earth don't they degrade over time and usage.

You would need a massive support network of grinding and life skillers to support having a few users of end game boss gear and they would literally  be the boss on whatever battlefield they walk on.

The masses would tremble before them in hopes that they could kill the beast.

The PK King