Fixing unique items is simple. Change decay so that once an item reaches 0% it will disappear or "get lost", and be added to a pool of items that can be discovered. The items retain their prestige bonuses and other bonuses. The simple change of circulating the same items instead of generating new ones would instantly encourage me to seek them and try to keep them alive as well as write stories about them and creating RP:s around them. I would likely go to great lengths trying to gain back the important items that are lost in one way or another, and would seek to build a reputation of some of the items as relics of a certain faith or emblems of this or that guild, or as traditional garments of a king or an emperor.
But right now, knowing that they will at some point vanish completely, I will not do any of the above.
I don't mind if I have built a lot of lore about the Holy Crown of Awesomeness and it is then suddenly lost - if I know that it will likely appear again at a later point - even a year from now, as it could become something like a holy grail for my character, perhaps even the defining aspect of him, adding more stories, more interaction, more intrigue and more reasons for going to war and create conflict. All with a very simple change for the better.
Actually, I would not even mind if the item lost its prestige and stats, as long as the name just stuck around.
