Well, why not? It'd make looting more likely and fun.
Only problem I see with rings/amulets being lootable is that it's abuseable. You can have someone make a character, create two rings and then he/she can "let" you loot them to get around the ring number restriction.
Now, if restricting the number of rings isn't an issue, then the above is not an issue. However, if you don't restrict rings, "once per day" or "once per hour" rings start to lose meaning, if you can cycle through a number of rings to get effect all the time.
I like the idea of more player-made stuff, especially with magical effects. I'm not sure of the best way to implement it in a balanced way though. I'll think about it, though, and comment more.
