Why do people always assume that the people of France are nothing more than mindless monkeys intent on marching themselves to the slaughter over something as petty as revenge? If Germany wins WWI, that's it. It's game over for France and it's place as a great power. In a little over a century, it has suffered total military defeat no less than three times (Napoleonic Wars, Franco-Prussian War, and WWI). Each successive defeat is more destructive and humiliating than the last, culminating in the complete destruction of northeastern France, the national economy, and the wholesale slaughter of it's fighting age men. This kind of national trauma in part led to the appeasement policy of otl. Despite France not wanting to allow Germany to become powerful again, they were not willing to fight a war over it until it became abundantly clear that war was coming anyway.
And the reason that the otl WW2 strategy was chosen and executed was because of the limitations that France faced even after being a victor of the first war, if Germany won, there would be no way that they could even dream of mounting an offensive into Germany simply due to the realities of the situation.