Attack and maneuver, maneuver, maneuver...buh bye Maginot Line, and all those front line French aircraft???. If someone breaches your defenses ( Maginot Line) like crap through a goose, how can you say the breached defenses were a “good idea”?
It was not propery utilized. First, the Maginot line stopped 300 miles short of the channel because the King of Belgium declared neutrality. Secondly,the French were using outmoded 1914 thinking unlike the Germans. The French philosophy was purely defensive. They devoted page after page of the First World War but did not heed Hitler’s warning that the Second World War would be completely different and they did not read the book “Achtung Panzer”.
On top of that, you had very incompetent generals on the French side who were between the ages of 60s-80s and they stifled new modes up thinking from younger upstarts. You can blame the French collapse on one person: General Maurice Gameline and the defeatists in the French Government