Yiddish is a language of Eastern Europe. It is utterly unknown to the Israeli Jews who came from North Africa, Iran, Syria and other Middle Eastern countries. There is nothing particularly holy about it. It was unknown to Rashi, Rambam, Ramban and many others. It was not spoken by the rabbis of the Talmud.
English is the language of America and international commerce. It is taught in many nations, e.g., all the Iranian Jews I know studied English when they attended Jewish schools/yeshivas in Iran. It is more important for Jews, who need to be well-educated to have parnassah and political power, to be fluent in English than Yiddish.