Well, the thing is Durge gets rid of Bhaal when they get resurrected by Withers otherwise they just end up as Bhaal's pawn even after killing the Elder Brain. There's also the implications from early access that the Tadpole and Urge were in conflict. So, there could be a temptation for a good but naive character to stay down by the river over being a mass murdering psycho. Maybe I'm thinking of "Daisy done right" but I really think even done wrong it's better than Emp. In my opinion, what the guardian does isn't temptation (the desire to do something, especially something wrong or unwise) because there is no drawback to accepting the tadpole powers like with accepting the Urge.

To be honest, I don't know if she was written just for a "conquest minded" character because there are different dreams for every other character. Sure, maybe conquest for the custom character which goes back to the terrible origin system of this game and your point about Larian's incomprehension of RP.

Also, I'm fine with it just being an evil path after all this is a setting with chaotic evil crazy characters, just like how a lot of previous games gave you pretty much two paths. Look at MOTB for example, which is by far the best DnD story expansion, there is no reason for a good character to accept the curse. Yet, accepting the curse path is pretty badass and gives a satisfying big F you to everyone out there.