I think Daishaclaire points out something quite crucial to this debate: About the games being narratively engaging.
Because that's were BG and IWD differ tremendously, but it might not look like it at a first glance, since "narratively engaging" is often confused with "good story".

Because, if you look at it more closely, the story (i.e. plot) in BG2 (which is often lauded as having one of the best stories in RPGs) is rather average and predictable.
Heck, the essence of it gets spoiled for you during the introduction cinematic and the epilogue! "Your character has unique powers; a mad wizard wants to steal those powers from you and had you kidnapped for that very reason. Now you must escape!" Gee, I wonder how that story plays out? ;)
However, where BG2 really *shines* is in it's narrative, i.e. how said plot is presented to the player. Also, there's party banter and romances that further add to this - and those were fairly new at the time of the games original release. That's, in my opnion, why so many fondly remember BG2's story.

Icewind Dale, on the other hand, doesn't feature any of this. No personal narrative, no engaging party members. But the plot is there, if you pay attention to it. I'd even argue that it isn't any worse than BG2's. Nor does this make IWD a worse game - just one with a different target group in mind.

However, since both games share the same game engine, gaming world and rules (mostly), it's easy to assume that both should have the same strenghts and weaknesses and gameplay. But they're actually very different.

Personally, I'm glad for it, because I vastly prefer the kind of game that IWD is and I think it's great that we got so different games! That way, everyone can play the way they prefer. That's great, no? :)