The surreal thing for me was that the only people I encountered who didn't speak (great) English, and forced me to rely on my mediocre 20-years-ago High School

The surreal thing for me was that the only people I encountered who didn't speak (great) English, and forced me to rely on my mediocre 20-years-ago High School German, were Turkish (fairly recent immigrants; I was staying in Neukoelln). You definitely would want to learn German for social reasons but it's absolutely not a prerequisite for moving there and being effective at most companies -- unlike, say, a top Japanese or Chinese company, or (from what I've been told) major French or Italian companies. In those places you might get away without good local language skills briefly if you're a specialist consultant, but it's going to make you pretty useless professionally otherwise, long term. I suspect a reasonably intelligent English speaker could pick up enough German to be happy socially in months, based on my reasonably intelligent English-speaking friends who moved there without speaking German beforehand.