Back on topic; Nothing communicates to the player that the tadpole is a consequence free power-gaining device. Omeluum tells you that although ceremorphosis has been put on hold the Netherese magic containing it can be instantly removed by whoever put it in place and then you instamorph into an Illithid. Only crazy people would be inclined to think the Absolute is going to give you any kind of autonomy back once you commit to her and the only reason I can think of to take her side now is if you believe your tadpole is there to stay and this is your life now. If we could ever communicate that ingame the Absolute would probably just detonate us remotely, though.
I think you are right that we will have options to become vampires and werewolves. I don't think it needs to be consequence free -- every evil person in Faerun, every person who sells her soul to patron knows they are going to suffer in the long term for their decision. Short term gain for long term cost is evil done right. Look at the original Valut of the Drow modules -- the people who are faithful to Lloth end up suffering endlessly in the demonweb pits. In Avernus anyone who sells her soul to Asmodus ends up becoming a pit fiend doomed to fight the blood war endlessly.
It just needs to be power gaining, not consequence free. The seduction of power is like the seduction of the vampire lover -- you know this could destroy you but you go along anyway. Again, this was the story of Bhaalspawn. The slayer could roflstomp anyone but it too often and you would lose yourself. In this, Larian got it right.
I would support some Astarian like musing for Tav "I wonder if there is a way to keep the powers without becoming a mind flayer"
