Czechoslovakia was neither a tyranny nor "hated" by non-Czechs under its rule. It was one of the few democracies in the region and while there were frictions, "hatred" is far too strong a word.
Hitler wanted war...if it was just about Danzig, he would have rolled into Danzig and the Corridor and left the rest of Poland alone.
Hitler was actually ticked off about Munich 1938, he was denied the chance to test his war machine in Czechoslovakia, he was not going to make that same mistake with Poland.