The items I like most are the ones with unique abilities like say Transform Kinetic Energy, it comes on one necklace that can be upgraded and on a rune arm. Items like this have a niche and since they're the only items offering that buff they can't easily be invalidated nor made useless by new loot. The only way to invalidate them is from system change, in the case of Torcs the incoming damage became too much so people put theirs away, as for new loot invalidating them the only way that works is if you put that effect on a better, easier to get items.
Loot invalidation happened with FoM, FoM got nerfed so many things it used to protect against before it now doesn't(it needed it though) and now it's also on plenty of items. Those old FoM boots from VoN used to be awesome but now you can get that effect pretty easily on better items or eternal potions.
So, I wish unique abilities on items stayed unique.