Tav isn't meant to be a character we imbue with deep feelings and a unique internal life from playthrough to playthrough, they're meant to be a vehicle we drive through the game to see stuff with.
Well if this theory is true, then they really need to reconsider their target audiences.
I believe possibly Astarion was designed to attract mainly female players (I could be wrong), and they expect that female players don’t imbue with deep feelings? Who did the marketing survey in Larian seriously lol