I agree with the OP - the loot system was most likely the least liked feature of the game for me. I actually don't mind the RNG that much, but the overdone scaling did bother me a lot for the same reasons mentioned already - it forced me to upgrade my gear at least partially every new level to stay relevant and replace that cool unique item I just found with something of much higher base damage or armour values.
One thing I haven't seen mentioned yet though is what happens when you actually over-level the content: you end up solely relying on buying your upgrades from vendors rather than finding them in the world, almost entirely removing the feeling of finding that super duper item at the end of tough dungeon or boss fight. This actually happened to me and forced mandatory vendor runs every level.
Also in my opinion the stats on items are generally just very uninteresting, even on the Unique/Legendary/Divine ones. The were very few cases where I wanted to stick to an old item because of the secondary stats rather than upgrading it with higher base damage or armour values.
Finally I also agree that Baldur's Gate 2 in particular nailed the itemization, but I also fondly remember Ice Wind Dale 2 in that regard. Both games had a very healthy mix of items you find in the world and items you could buy from vendors to supplement your finds.
