Ah, I mentioned that in my opening post, and I wanted to bring that up, how would item decay work best?
On a time basis, will rob players of items they never use but want to keep. Kind of like Puzzle Pirates, where most things have a life span of 1 month, then it vanishes from the face of the earth. I can see this being good for food, where players need food, but you can't horde food because it spoils after so long. Other items may also apply to be treated like this.
By use, weapons and stuff that have limited use will cause players to resent the developers for only giving their sword 500 swings or somesuch. I have a memory though, of a game based on samurai that gauged the durability of your weapon based on a meter, where with every strike or parry, the meter goes up a little, and if it fills up, then the sword breaks a little, and the meter becomes shorter, and thus the sword is less durable. Once the last bit of the meter has broken, the sword breaks, and you have to get a new one. You worked around this meter by being conservative, and if the meter becomes almost full, then you stopped striking, and the meter would empty itself.
I think something like that would work well, for weapons, and perhaps for shields and armor and stuff like that.