why is it so hard to just allow keyboard & mouse players to just drag and select?
This is a really good question.
Or Shift + click for multiple selection from portraits. The two most intuitive selection methods used everywhere else.
But no, no no. Larian knows better because it was time the wheel got reinvented. It's better to have a clunky chain / unchain all system without the ability to easily select 1-4 PC's. Where members of the party often get inexplicably left behind when they got ungrouped for some reason. Where PC's run in circles through hazards like headless chicken after battle because 'follow' is always on.