Yeah, France got played like a damned fiddle. What also sucks is Bismarck didn't want to snatch up Alsace and Lorraine, but public pressure in Germany after such a decisive victory forced him to make those demands.
Yeah, its real easy to march on a city when you've already sacked the countryside of supplies and need to retreat with what you have or risk total annihilation in the face of a foe with both manpower and materiel superiority. Oh wait... Once again, you display your ignorance of the actual situation. An army with supplies, a reduced baggage train thanks to railroad supply lines, and wounded who can be safely bivouacked away in rear areas can march a lot faster than one with limited supplies, wounded that need to be carefully moved to prevent further injury, and a long baggage trail that needs protection against Union cavalry raids. And raid they could given that the Confederate cavalry had shared in the beating, the Northern mounted forces finally proving themselves an equal.