Of course sometimes hashkafos/ideology change.
Do you think a secular language (English) being the dominant language in the yeshivish world would have been tolerated in Europe? The hashkafa was to speak a jewish language which English certainly is not
It was AGAINAST all the gedolim to move to the United States before WW II. That was not a hashkafa, that was the halacha, Of course after the war such a halacha could not be kept anymore