I think it's a bit different - these communities (which BTW are a minority even among orthodox religious Jews) choose to speak Yiddish and not Hebrew to express their detachment and disconnection with modern Jewry and specifically Israel. Secondary consideration is the status of Hebrew as the holy language, not to be used in mundane and profane matters. This was long the case in the Jewish diaspora, but with the start of the Haskalah project and the idea of Israel as the Jewish state, this has changed. These communities have not accepted these changes and thus try to preserve their way of life as it was beforehand. The use of Yiddish here is more of a consequence than the reason.