Being locked into a board means more chance for injuries.
Toes and feet get hurt when you can't get out of straps.
Knees/ACL's pop when you can't get out of boots.
Considering about a race board, that is longer and wider than any other type, it would have even more leverage against your body in a crash, and could really hurt you if your feet were locked to it.
Plus the glassing would be a huge pain in the ass, and what if you made the foot position an inch off? It would not be easy to just move it to the next insert, or add an insert.
Structurally the board would be weaker and heavier than one with a normal shape.
And harder to control flex.
So there might be some problems, but maybe you can prove me wrong....
If I wanted something like that, maybe I would go for a contoured foot pad instead, could be applied to most any board..