And yet on that smaller budget IWD-devs managed to implement some unique dialogue choices. And if you look closer at BG2, the mechanics required to implement this are often already there. For example Bodhi will refuse a pure thief, because a thief siding with the vampiric guild would lose the stronghold. Multiclass thieves she is ok with. Which in my opinion doesn't make sense. Would it really be so much more expensive from a development standpoint to have Bodhi refuse a paladin or a good-aligned cleric instead? I doubt it was a matter of resources.
Why do you suggest that stat-gating dialogue choices has something to do with budget? Or ability? If the BG2 crew had wanted, they absolutely could have stat-gated a lot more. It wouldn't have been difficult, it would merely have required a lot more dialogue. Do note, however, that there are some charisma-based dialogue options that only work with high charisma. You can't talk your way into spellhold with low charisma and you can't convince the Drow girl that you have performance problems either.
And Boddhi refusing paladins and good-aligned clerics would open a different can of worms, forcing players to consider whether it made any lick of sense that they were allying with the shadow thieves? If they have good alignment then no, that makes no sense at all. There was, I believe, some work being done to have a third option also, but it just never got done and in the end they had to settle with super evil vampires or super evil thieves, neither of which is something good-aligned characters would care to ally with rather than murder to death.
