The fingerboard and bridge are curved so that the bow can select strings to play. If the board and bridge were flat, you would be unable to isolate the center strings. If you are referring to the slight curve down the length of the board, this is supposedly to give the strings room to vibrate when being played. An extreme up or down distal bend of the fingerboard would be bad.
Why is there a bow on the fingerboard?
The fingerboard and bridge are curved so that the bow can select strings to play. If the board and bridge were flat, you would be unable to isolate the center strings. If you are referring to the slight curve down the length of the board, this is supposedly to give the strings room to vibrate when being played. An extreme up or down distal bend of the fingerboard would be bad.