Yiddish is far from useless. It is the language that torah was passed down with for a thousand years. It is similar to how the gemara says not to take Aramaic lightly, even though it is a non Jewish language.
When I learn, there are gemara ideas that i can’t explain in English or lashon kodesh; try saying “rashi firs ois” in Hebrew or English, or “bavorn” – there are terms that are part of the fabric of learning that are exclusive to yiddish. I’m sure ladino and other judaic languages had the same.
Your personal feelings are completely clouding your judgement. What would you tell someone who hates Hebrew because their parents verbally abused them in Hebrew? You’d say to suck it up and see the supposed objective truth…..
I’m genuinely offended at the suggestion that a torah language that my ancestors used is useless.