The blog also said using the tadpole too much can affect your relationship with your party members and even affect your romance. So while it is mainly a roleplay thing it also seems to greatly affect the game's story as well. If you abuse the tadpole and become immensely powerful so you can save the world I imagine the ending you get will be a bittersweet one at best.
I'd argue that the tadpole affecting the narrative of the game is just as important as any pure gameplay effect it might have.
