I would love it if enemies always had whatever weapons/equipment they had on in their loot after you kill them, but it could be a balance thing like not wanting players to have 20 longswords and assorted armor pieces to sell to the first trader they come across, just looting the goblins from the very first goblin encounter would net you a decent chunk of gold if they all dropped their equipment.
BG solved this problem with encumbrance. Loot had weight, and you could only carry so much of it. All of those Hobgoblins around the Friendly Arm Inn dropped swords and armour, but you couldn't possibly loot and sell all of it without making several trips. Even within the same map it just wasn't worth it.
