They didn't say they didn't want to did they? You imagined that. It'd be fantastic to be able to learn the languages of all the countries you visit, but not everyone finds that easy do they.
The OP didn't talk about visiting a country, he asked about settling in Germany. The words were "do you have to", not "I wish I could"; he made learning your adopted country's language sound like a chore instead of a challenge. Full immersion makes the learning process much easier.
Besides, taking citizenship of any country requires a language exam.
Besides, taking citizenship of any country requires a language exam.