Having a filter for shows by language spoken is something streaming sites should have but I don't see a reason the default settings should hide shows that still have subtitles in your native language.
I strongly disagree that shows in languages you don't speak are "a waste of a potentially good show". If you read slowly or dislike reading when watching shows I understand why you have less interest in them but if you can keep up with the subtitles I don't think you should completly disregard them.