re: Should the Entente have invaded Germany at end of WWI?

You're looking at it from the "now" perspective. You have to imagine the scenario you propose at that moment in history. You're asking, should the Entente, when Germany offered what was effectively an unconditional surrender, turned it down and continued to fight? What would they have kept fighting for? For Germany to surrender even more abjectly than what they had already offered to do? That would have been impossible. The Allied leadership would have been asking thousands, if not millions, more men to die in order to gain something they already had for the taking. There would have been riots and revolutions had they tried that. And if they were concerned about future German revanche, which would have seemed more likely at the time: that Germany would seek revenge for the war the way it ended historically, or that Germany would seek revenge for a war brought into her homeland after she had offered to surrender unconditionally?