Iacisrmma, you would be surprised at how quickly small children pick up a language.
Joseph,
Actually the Sheeta Mekubetzet says that it the Raavad questioned if someone is yotzi talmud Torah in a gentile language (and Yiddish is not even a language but a corrupt form of German). A person who speaks in Lashon HaKodesh merits Olam HaBa, Geula and long life (Yerushalmi Shabbat 1:3). The Gra considered speaking it to be a mitzva and spoke it himself (Biur HaGra YD 245,10 and Responsa Divrei Yetziv YD 52-53) as did Rav Kook (in fact, when Rav Charlap first met him he addressed him in Yiddish and Rav Kook informed him that he was not to be addressed in “Jargon”).
The language one speaks influences one’s mind-set. Thus the more one speaks in Lashon HaKodesh the more kedusha he internalizes. Ezra very much lamented the linguistic situation in his time. However, we see from the Mishna and Gemara in later times talmidei chachamim spoke it although more so in EY (holy land, holy language). It could be that the Chatam Sofer means that the people in Tanachic times added words from other languages to express foreign concepts as did the Tannaim (who sometimes used Greek and Latin words).