But isn't that the Gretchen Frage?
(Sorry, german is my native language, and you were quoting Goethe, I don't know the proper translation)
I think they did that part quite well.
You have this tadpole in your head, and a lot of people tell you, it's bad.
On the other hand, there are people (e.g. Astarion) who obviously profit from it.
So if course you know from the beginning, it's a Faustian bargain, as you put it.
So, the Gretchen Frage is: do you want to use that power or not?
Faust had the same decision to make. Use the power of the devil or not?
Of course, using the powers of the devil has it's benefits, you see a lot of things you could never imagine!
At least at the beginning, it seems nice ... Be it dreams, or whatever