Okay, so I think this may be the issue. Huge quantities of ‘unique’ items but every item looks almost identical from a token point of view and most of them seem to have largely irrelevant minor effects that make it harder to decide whether to junk or not. Many of the effects are highly circumstantial so you save them just in case but end up carrying round loads of crap. Like 10 different varieties of arrow clogging up your inventory. The implementation in the original game was actually better I think.They definitely had this many items. What they didn't have was the sheer variety of neat effects and riders when you cast this or that, because the game system couldn't handle anything that complex. So you got piles of +1 and +2 items dropping off every enemy, instead of unique stuff. The only games that were somewhat exempt were the starter games like Pools of Radiance and Champions of Krynn, since item escalation didn't really kick in until later games (Pools of Radiance had a bucketload of art items though).
BG1 goes pretty gonzo with Tales of the Sword Coast. NWN had quite a few in Undrentide, and goes totally crazy with items in Hordes, etc.
When it comes to buying items they are largely worse than what you find and the traders don’t seem to have enough gold. So I sell a ton of stuff, end up with nothing to spend the money on and it just becomes a load of bureaucracy.