What motivates you to play a long CRPG? I am sure the Larian game writers talk about this quite a bit. I guess BG III starts out with the PC getting stuck with an Illithid worm or something, with only a few days to live unless it can be removed.
We know that tadpole you get is not the usual tadpole. It was made up to accomodate needs of the game. I will wager that we won't be able to remove it that easily, out initial attempts will fail, because it is a different kind of tadpole and it will remain through the enitre or most adventure.
It's been said that giving into tadpole give power but corrupts - as well as taking or rejecing this power will be one of main throughlines in BG3. I don't think it is a big jump to claim that tadpole and embracing or rejecting Illithid is BG3's version of Bhaal heritage. I also think it can be very much like source in D:OS2 - something that ties companions and coop players together and includes them in narrative, over-riding any personal needs or motivations an origin or custom character might have.
There are too many things tied to the tadpole (explanation for your superhuman abilities, connection to companions, ability to read each other mind and share experiences) to just remove it in first act. Collar in D:OS2 supressed abilities acting as a tutorial gate in some way. Tadpole is the source - it is through it that gameplay system are being implimented/explained.
