Tomche -“So to cause Loshon HaKodesh to be used as a street language, complete with all the disgusting ways it is used today in Israel, is just more of a reason why we should make sure it never gets into the streets.”
You’re basically saying like Sam that LK can exist in Ivrit, but you’re saying it’s Ossur to use it. I disagree; even if you say LK can exist nowadays in modern form -you can speak Ivrit. Because I hold Ivrit is Not LK and it’s a new language that was made up. (It’s not even a Jewish language.) They have a different pronuciation than LK amongst other reasons. If it would be LK because LK can be spoken in modern form -then speaking Ivrit would be Ossur. Many Choshuv Jews have spoken and speak Ivrit.
What your saying about Yiddish is true. Klal Yisroel did this throughout the ages. The Medrash says Hashem said Anochi in the first commandment of the Aseres Hadibros so Klal Yisroel could understand. The Jews at that time didn’t speak Hebrew. They spoke a dialect of Egyptian. “Anochi” was part of this language. Acc. to this Medrash that’s what it means Shelo Sheeno Es Loshonom.
They didn’t want to speak Egyptian like the Mitzreeyim so they spoke this dialect – which they (the Jews) only spoke.