I disagree on the Bhaalspawn freelancer part, if the Bhaalspawn is evil and doesn't care about saving Imoen or going after or getting anything from Irenicus, then I can see the Bhaalspawn sticking around gaining more power money, powerful items and more benefits.
I do have a question for you, most people prefer SOA to Throne of Bhaal because TOB rushes you and forces you to go about the Bhaalspawn saga. Whereas Shadows of amn has a lot of freedom. What are your thoughts on TOB? Do you like the story/narrative and how they went about it?
I might be wrong, but as far as I remember, when you recruit new companion your options are more or less: "But you should know that my real objective is saving my friend" or "But you should know that my real objective is getting revange on an evil Wizard". I don't remember there being a neutral option "at the moment I am just doing stuff". Getting to Spellhold is our protagonist objective, even if we get distracted from it (I think intro is short enough for new players to forget about it. That what happened to me on my first playthrough). I see it as imposed limitation on player - just as it is assumed that Shepard wants to stop reapers, Geralt wants to save Ciri, PC in Kingmaker cares for his kingdom. Though it is true that PC has no reason to think Imeon or Jon are going anywhere, and so he can take his time. I generally struggle playing evil characters in Bioware games (there is not enough logical explanation nor incentive for being evil). Still, I think there is a disconnect between what narrative wants you to care for, and what the game makes you care for. Still, it is a small sin compared to other RPG, like Pillars or Kingmaker.
As to ToB, yeah I don't like it. It has "Return of the Jedi" syndrome - not great, but well concludes our protagonist story, so it's essencial. ToB biggest problem is big story, contained in an expansion - there is too much happening for it to have proper time to breathe. It also dips into cosmic stuff, which to me who is unfamiliar with FR universe, and even less so at that time as it was my first FR game was rather difficult to relate. Too many straight up exposition dumps (and now a ghost of Gorion with tell you all the backstory), too many Bhaalspawn I never care for to kill, and an underdeveloped villain. It's also all too "high level for me" with planes, superduper monsters. Big stakes and yet rather underwhelming.