By the way, this might be a really really dumb thing to say on my part, but the low resolution suits BG1.
Why?
BG1 is a wilderness exploration game, among other things. Games based on moving across the wilderness have involved only being able to see only a little of the area at a given point of time. Think of the thick foliage of the Elvandar forest in Betrayal at Krondor or the gloomy Neverwintan forest in Icewind Dale 2. You were stuck in a giant forest, with visibility extending only till a short range. In case of Icewind Dale 2, the forest was broken up into several small areas.
For this reason, I play the game on windowed mode, when I do, and not use any resolution mods. The game was not made for higher resolutions. Indeed, at higher resolutions, the world of BG1 seems to contract immensely. Same for the first Fallout, where a high resolution mod could allow you to see the entire map, and really diminish the sense of having to explore any place. Torment on high res also makes Sigil look like a small bowl in which the world is concentrated, rather than an endless stretch of slums and buildings.