I don't see the reason for mana evaporation either, but its part of vanilla mabinogi and there's a very vocal minority who want to keep it.
Mana evap is there for lore reasons and as a way to punish magic, as the first director hated magic. It's the kind of thing that makes sense in the lore, but gets in the way of gameplay and should be either reworked or removed.
This is similar. There's no reason for gear to really degrade by simply wearing them. They already degrade from EVERYTHING ELSE, getting hit, using them, I think rain was proven to increase passive dura loss at some point? Don't quote me on that last one, could be totally wrong. Furthermore, this feels like a system that might have been implemented for realism but ended up being exploited for money, as gachas used to spit out unreparable items (and there are still plenty of unfixable stuff in live) that will eventually die from nothing, forcing you to try for more if they aren't limited time.
Not only does durability force players to go out and earn and spend money to keep items in working order, it also keeps blacksmiths and other crafters a lot more relevant to everyone, even those already with their fully enchanted and upgraded weapon, unless it's an ego, it will have to be replaced eventually. There's a reason why upgrades and such don't take very long to do. Enchanting is risky, but you gain a lot of power in doing so meaning that it's easier to gain cash and replace the weapon or maybe even work towards something better. This is what durability does for the game.
I'm a bit confused on the "un repairable items" part of your post. Those weapons are generally not something that are meant to be kept long, nor are they fair in terms of damage, if we're talking weapons. Things like the pivotal longsword, machetes, and so on are not meant to be repairable as they generally have high max with no real commitment put into them. They're one off weapons meant to be used and discarded. I don't think unrepairables have ever been the things that sold gachas. Now for unrepairable clothing, suggesting to make that repairable is a fair deal, because its hard to come up with a reason for why anything is unrepairable that's purely cosmetic. It offers no high max bonus or anything of the sort, they're just outfits that can't be repaired.
For limited items, like say a wing bow or a dragon sword, the problem is not that durability exists meaning that these weapons will eventually die(probably not the wingbow because everyone egos it), the problem is that you cannot potentially find these items in game through playing the game. Maybe a specific mob could drop the pattern or end room chests. This would fix the problem of certain limited items not being able to potentially be replaced through actually playing the game.
To comment on OP, as someone who doesn't stay logged in afk at all, I don't see how this is an issue, but I can see it being a problem if you're afking for a significant amount of time, but, all you'd have to do is take off your clothes.
FYI, the final message is not intended to be rude, apologies if it sounds that way.