Why wouldn't you want to? It's a lovely country, with a huge body of literature that you'd deprive yourself of if you refuse to learn the language. And why isolate yourself from the locals? Weird attitude, that.
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.
By "stick around" I really meant stay/work for a few years (like 5 or 6 years) not settle down permanently in Germany.
And yes, I agree if you going to live permanently in a country you should know the local language and also imbibe the local culture to a certain point.
As a native German, I'd say it is essential in most parts of the country, except in a few urban areas such as Berlin or maybe Munich. But generally, for integration purposes (and also for better dealing with the infamous German bureaucracy), staying in Germany without learning German would become pretty painful after a while.
While you can "survive" in Germany w/o German and may be able to work in an international IT company when it comes to "living" I have yet to see people sticking around longer who did not learn German.
Some large international companies, Dräger where I live, for example, have fully English departments (they employ a lot of grad students and post docs). But when those who never planned to stay forever start learning German soon after they arrive.
You probably will need to learn german and to find an employer that likes you enough to jump the beurocracy hoops for you (signing that they couldn't find any germans to do the job with some proof of rejected german candidates).
Depends on the area of work I guess. It's not that uncommon to have English as company language in startups or IT companies in general, but even if not you'll get around with English just fine.
Why wouldn't you want to? It's a lovely country, with a huge body of literature that you'd deprive yourself of if you refuse to learn the language. And why isolate yourself from the locals? Weird attitude, that.