ps. at like 24:30 or thereabouts, that's such an excellent thought, like what if IWD had been the game to showcase all the new engine stuff that dropped in BG2 a few months later? I just imagine how much more interested I'd probably have been in playing as Sorcerer or Barbarian or any of those special Class kits in IWD as opposed to BG2, where I immediately felt like my Charname would somehow be detached from the BG1 Charname. IWD didn't have any of the baggage and would have been sorta the optimal setting to introduce a class like Barbarian or a race like Half-Orc.
Also if it had had the new weapons and spells, there was more meat on the bones in IWD to custom spec, esp if using the BG2 scheme, to create a fully custom party with all those extra weapons and skill proficiencies. Or stuff like setting traps for the rogues or whatever else was added in for the main BG2 engine package that followed so hot on the IWD heels.
Also there are some sprites where I actually still really prefer the BG1 engine visualization. For example the chainmail armor on humans and the shields with the regular round, kites, or tower shields, (I just always though everything in BG2 was a bit spiky, like even the bucklers? hehe) but then for the most part the BG2 sprites and higher res was just sorta undeniably better, and pretty impressive by comparison, which made it harder in the afterlife I think once BG2 had already come out. To me the Goblins that I associate so much with BG2 are really IWD gobs, so there's little things like where BG2 gets all the credit, even though IWD really should. Also BG2 was able to leverage the fact that the IWD portraits and stuff like audio barksets were more or less totally compatible and ready to plugin to BG2, meaning if you had the IWD game, pretty easy to switch those in and have at least a couple dozen more options for BG2 portraits ready to rock. The dilemma I always found was that it was a little hard to combine say half the party using the Sass BG2 portraits and the other half using IWD portraits. For me I always had to go sorta all or none, but to me the IWD portraits were just so much cooler looking. At least for the time, it was best in class. I mean that was whole set was pretty next level, and then when they brought Sweet on board for the sequel to do all the Drow and such, that was pretty badass! But if BG2 hadn't had the benefit of all those IWD assets already existing, I think it might have seemed slightly less epic. Mainly since all the infinity engine games had that angle like, import your own if you want. I think that was what set them apart from other similar games. Import/export