Explain why gear durability could ever make a game better and more enjoyable rather than the opposite...

It works well in Breath of the Wild because you're expected to quickly cycle through many different weapons. I actually prefer that way to a slow degradation.

I get that it's realistic; especially in the first dead rising but having a broadsword or katana disintegrate after however many uses is just as immersion-breaking

Because immersion > zoomer catering

pick up one of the magazines then

The idea is to stop you from using one game-ending weapon, in most games. BOTW for instance makes you want to not just use a guardian blade you pick up 15 minutes in or something, but save it for a tough fight instead.

Dark cloud is an interesting case, it has repair powder and upgrade systems that reward you for using one weapon for long periods of time. The durability exists more so you can't spend forever inside the dungeons diving without going back to town for more supplies. You use weapons to upgrade them and fuse upgrades to the weapon when applied. It makes you judge whether it's worth using durability (and powders) in a less difficult area, or to save it for grinding tougher monsters for easier upgrades.

Durability is good only if these 2 things. If the enemies are also affected, and if melee weapons crit on breaking.

Yeah you're right, the katana should break after the first swing

This. Oblivion's is also nice since gear takes years to degrade and can be avoided entirely if you're a mage or an unarmed guy in clothes.

I always thought the main reason they broke like that was because they where shitty mall ninja swords

No. Are you? Git gud.