I do think Germany got a crap deal at the end of WWI. WWII as well for that matter. Soviets should never have been in on the conferences, given they had about as much blood on their hands as the Nazis, but that's neither here nor there.
Anyway, I do think they had some legitimate grounds for military action, had they been unable to get their land back diplomatically. Unfortunately they were looking for an excuse to fight, and found one.