For the past two years or so the hotels (at least the ones I stay in) in Frankfurt, Berlin, or Munich don't ask for my passport anymore. Sometimes I put it on the counter and they politely say 'Not necessary, sir.' I usually stay in the same hotels but it may be 4-6 months between visits so I doubt they remember me but who knows.
But hotels in Dresden (Saxony) are anal about it as are Czech hotels.