The problem is: Before Hitler's invasion of Chechoslovakia Europe had a bad conscience because of Germany. They said to have introduced the right of self determination. But that was only done not for but against Germany and Austria. Their rights were violated in 1919 (and 1945 as well...). So the Germans in the Sudeten were not allowed to join Germany, Austria, too, parts of Silesia were departed against a plebiscite, that plebiscite concerning Eupen and Malmedy was a farce, Tondern and Appenrade were given to Denmark despite a German majority (infact the election circles were made to have the Germans a minority...), West Prussia was given away despite a strong German population (in the latest census there was a German majority in that province). So when Hitler cam to reclaim it, it was seen as legal.
IMO the problem was not Germany getting it back, but Hitler earning the fruits others, especially Rathenau and Stresemann, had planted.
And so we return to Versailles...
Adler
Many people in the West understood that the problem was not Germny getting the areas populated by germans back, but rather that it was pretty clear that Hitler would not stop there.
The argumet used by the appeasers was precisey that Germany was "only taking back the lands of the germans", while the "hawks" pointed out quite correctly that the Nazis had no intention of stopping there - as they didn't.
It would have been far better for everyone, including Germany, if Britain and France had stopped them when they violated Rhineland (again, the problem is not re-taking Rhineland per se, but rather the context in which it took place).