I am thinking that the idea is that if you use the tadpole, the effects happen to you sooner. Thus, in Act 1, you have the dreams, etc. and can use the special powers because you are actually giving in to the tadpole. I think this is Larian's way of making it feel as if time is progressing. You can only use the tadpole's gifts a few times a day. Then you have to rest, and so you progress time quicker and see more tadpole effects quicker.
So I'm thinking that Larian is going to still have you experience tadpole effects if you resist, it just won't happen until maybe Act 2 or 3 because you are being good and resisting its control. Still, like Raphael says, "Go ahead. Shop around." He's implying that even if you resist the tadpole eventually it'll catch up with you and you'll still have to go to him in the end.