One problem with having France go first (among others) is the time line would be incorrect. Fance was not neutral having declared war in 1939 after the invasion of Poland.
the game actually begins on the eve of the invasion of France. Demmark and Norway where captured by Germany in April of 1940 and are already in German hands at teh start of the game. The UK starts with control of Iceland, where infact Britain invaded Iceland the same day Germany invaded France.
Having France go first and you would have to back-up the game timeline from where it was designed to start. Also, having the Germans roll over the French right off the bat is the way Larry wanted this game to work. Changing that design concept makes this a very different game.
Kim