This has come up with a number of invasions as well, over the 15 years I've played.
Go back to the invasions of 2005. After way too many players complained, they made it to where the invasion spawn didn't loot.
Yet, with each new event, they forget the lessons learned from the old ones.
It's NOT that the enchanted items are getting looted individually (I've found ONE so far, on the corpse of a paragon balron after it combined). It's all the OTHER stuff that's getting looted by creatures with a fast decay rate. From one lich, after it died (there were only two of us fighting the spawn at 3 AM) I recovered THREE items from it before it decayed, from my backpack - NONE of which were enchanted items, and all where non-insurable from being containers, gold, etc.
The paragons don't seem to decay as fast as the regular spawns of the same creatures that fast-decay. (artifact of the paragon code? a change to increase looting of a chest that might be there???)
The balrons and mummies appear to have semi-normal decay rates (long enough for corpses to combine), especially if they chase you out of the rooms into the hall. The Balrons loot; the mummies normally are BAD for looting elsewhere, but I've not seen one loot yet in there (legacy code from a previous event?).
The daemons rarely loot, compared to their non-event counterparts - but in some rooms, they seem to decay quickly while they don't in others.
The Liches and lich lords are looting fiends, and tend to loot players most often in the rooms where they decay at the champ spawn rate (before the instanced corpses combine).
Other mobs (that mainly show up in Jack's room) also loot normally, but I don't see them enough around bodies to see if they loot.
I don't mind the fast-decay bit per se (and love it for all the low-end, non-looting, crap), but for events (and even champ spawns), there should be some sort of toggle relating to looting or decay.
Either make them not loot in their fast-decay form, or make the presence of non-gold looted items in the creature's inventory force its body to go through a normal (not accelerated) decay cycle.
If it's the ROOMS causing the quick-decay (corpses fast-decay there, but not in the hallways), it would be far better to have most of the spawn function like the Khaldun creatures that leave no corpse, and limit their loot (which drops to the ground) to things like T-maps/chests (as paragon chests check separately on the T-map chance - as you can get both off a paragon). That way, why you might get looted, someone may recover your stuff (and if they are nice, return it; if not nice, well, all's fair in war).