One of the most annoying things I am coming across is the insane level of useless junk that piles up in my fortress.
At the bottom of my river, inaccessible to any dwarf, there are 7 or 8 full sets of goblin regalia, complete with goblin bones. This stuff has been there for years now.
Outside my fortress for the last year, there is a full trade caravan of elven goods, scattered across the entire upper plain. There is a mix of Goblin and human junk from the human caravan later that year.
All this crap is going to sit there pretty indefinitely, since I cannot afford a group of goblins to sneak in and slaughter my dwarves as they try to grab the junk outside.
Therefore, I propose "Enviromental Degradation" of useless junk, where they are removed from the game if they sit in certain environments for long enough, based on their materials.
Things in lava should have no time at all, which they do. Things in water should have a much extended time limit but a set time (like cloth goods which have been in the water for forever), while things outdoors should take even longer (especially in dry climates)
But they should eventually go away!
On the same side of the coin, these items count as goods that can be stolen from the fortress. How about a flag that if it hasn't been interacted last by a dwarf from the fortress, it isn't listed on actively owned inventory, and have a list of "Unclaimed" in the fortress stocks instead, listing everything that came from slain caravans, rather then cluttering up the "armor" tab?