I just found myself comparing my experience in Baldur's Gate and Diablo 3: Raiders of the Infernal Department Store. Two wildly different games, true, but I found it ironic that, while one of Diablo 3's selling points was compulsive and awesome looting, I simply couldn't be any excited when Demon Invader number 667# would spill another pair of pants.
I was once told that one reason for that is the attribute metagame in the Diablo series was simplified, items don't compete with each other simply because one yields more 'DPS' than the other. There's no question of what is actually best for your character (which is fundamentally equal to every other character).
I can't tell if that's true since I haven't played Diablo 1 and 2, but my own experience with other 'diablo-likes' supports that argument. But I think there's more: I believe that the attribute metagame isn't enough. Which brings me to Baldur's Gate.
In the first game, simple enchanted items are relatively rare. Items with specialized and higher bonuses (such as +X against Undead) are even rarer. Items with special abilities are almost self-contained to the expansion. This denotes one difference between BG and Diablo 3, loot that is meant to be interesting are rarer and, therefore, actually interesting and meaningful. But progression is still linear, since its still mostly about the attribute metagame. Every party member fills a niche, meaning that each party member will benefit the most of a given attribute increase, items are still simply better than each other.
Granted, if Diablo 3 had managed to accomplish this much, I'd have been pleasantly surprised. But the IE games, I believe, went beyond that.
In Shadows of Amn the structure is mostly the same, but there's more loot and the stakes are a higher. And with a higher power level, you can have more diverse items when it comes to special abilities. I remember hoarding a number of rings, cloaks and such, not because of different attribute bonuses and the like, but rather because of special abilities.
This is something else that loot in Diablo 3 didn't have, creative and situtional spell effects. For the most part, I might wear that cloak of +X protection, but I'll occasionally switch into that other one that transforms me into a troll for healing purposes. And it might even remain useful levels and levels after I acquired it.