Countries have been battling for centuries, and claiming land as victories. So, did they do it out of morality, or because too many countries were involved, or because they were all nearly bankrupted?
They did. At least, the USSR claimed half of it - the GDR (German Democratic Republic) or what we used to call East Germany. East and West were only fully reunited in 1990.
The allies didn't claim the rest for various reasons, I imagine the moral ground (the war started over an invasion) and economic issues were foremost though.
I think there was a realisation that WWII started because of the severe terms of the Treaty of Versailles at the end of WWI which left Germany impoverished and bitter and ultimately in the hands of a dictator, Hitler.
The argument was that if Germany was helped economically, it would grow into a peaceful democracy and there would be no more wars that they would start.
Which, happily for us all, proved to be exactly the case.