As long as Germans remained in The Sudetenland, they were bound to make trouble again down the road. They proved by their past behavior that they wanted no part of being a part of Czechoslovakia.
Maybe they should not have placed 3 million ethnic Germans in a Czech state that had never existed before without giving them any sort of democratic vote on the matter in the first place. Maybe the Czechs should not have set about oppressing them right from the start. You see, this was not a one sided affair where those mean ole Germans just started making trouble for no reason......