By paired items I mean worn items that you need 2 of to complete the set. Essentially anything that gets equipped on the hands or feet.
Instead of a "make gauntlets" job producing a Left and a Right Gauntlet, and both of those having a separate quality modifiers, the job would be changed to create a single Item that grants coverage over both hands and could be called "Steel Gauntlets". It wouldn't be 2 separate items handled as one, it would be one item with all language that refers to it as being plural. Thus, no decoration conflict as the dwarf is technically decorating one item, but is understood in the descriptions and language as having decorated both of the gauntlets..
Where weight is concerned, a single Steel High Boot weighs 3Γ, and a steel gauntlet weighs 1Γ. The extra weight is marginal imo, but when worn by a dwarf missing the appropriate second limb it wouldn't apply the extra weight since the limb is missing. And, while we're on the subject of weight, a steel flask weighs 7Γ compared to a Steel Mace which only weighs 6Γ. How crazy is that? We should use those are blunt weapons instead. First we bash your skull in with it, then we slate our thirst.
I think that system would be simpler over all. The items aren't produced in singles, and if a single boot is stolen/goes missing, you'd be creating 2 anyways.
If you have 100 dwarves each need 2 boots, and 2 socks if you're generous. That's 200-400 items right there. Do this though and it'd cut the amount of all foot and hand worn items by 50%, thus saving a bit of FPS.
Lastly, the artifacts. You wouldn't have mismatched artifact gauntlets or boots.
The only downsides, imo, is that some people like that little extra bit of complexity. And, artifact gauntlets and boots might be a little more epic if produced in singles.