Where do you get "crumbling to dust after thousands of years"? There is still Ayleid armor floating around and it's in perfect condition, not to mention you do a quest in Oblivion where you retrieve an Ayleid helm that had been sitting in a ruin for thousands of years and it was made clear that it looks like it was brand new.
The only instances of Ayleid items in Oblivion I can think of are the crowns in the Collector quest line, and the weapons "Ancient Ayleid Mace" and "Ancient Ayleid Sword" that you can interact with after defeating these: http://www.uesp.net/wiki/Oblivion:Ayleid_Guardian in the Thieve's Guild final quest. They're scripted to disappear with the message "such and such crumbles to dust as you pick it up", or something like that.