Yes, I understand all your arguments.
But a long box with a "looong" rigid finbase (stiff g10 base) will spread the forces antagonizing the torque in its hole length (force x distance). For a given torque, a short arm will create a higher force. The extreme example of a short box/finbase is a simple screw fixating the fin to the board. What will happen? the force transmitted from the sail ect to the board is still the same. In the future I really hope it will function with the short US- as I love the starboards.
Many years ago there was a similar discussion at the star-board WEB site. (Carve 99 and single footstrap with tuttlebox). I remember from the very beginning that the starboard team was listening to the people out there. I´m sure it will progress in the same line for the future.