Among my family/friends/co-workers who own BMW's, none of them have done any sort of preventative maintenance. Actually, the only one who had his water pump break down was in his 1985 BMW 5 Series at around 185,000 miles. So, for the general public, PM is a nonexistent thought.
I'll still get the cooling overhaul eventually done though, as I'm all about "peace-of-mind" and not having a car leaving me stranded. My old 300ZX did that too often.