Hitler was always playing a bigger and longer term game. By acquiring the Sudetenland he took out the very strong defenses the Czech's had along their border with Germany. That made taking the rest of the country a walkover. And having Czechoslovakia's northern border completely outflanked Poland, the next bite of the pie and the final straw for Britain and France. Stalin went along a) because there was really nothing he could do to stop Hitler, and b) being handed the eastern half of a country that was even more troublesome to Russia than it ever was to Germany made for an extremely nice (however temporary) bribe.
We'll have to wait and see if Putin carries through with the rest of the playbook and gobbles up all of the Ukraine and not just the Crimea Peninsula, which is mainly Russian speaking and was, until the 1950's, part of Russia. But with the Crimea dangling out there with no land connection to the Rodina, another WWII analogy comes to mind ... German speaking East Prussia (now part of Poland and then separated from Der Vaterland by a Baltic Sea facing section of Polish territory). Putin may go forward in steps by demanding a Sea of Azov coast corridor.
Mourir pour Dantzig?