I think the deal with the "Ring" is that its by far the most demanding circuit there ever was, for both driver and machine. Japan, although full of amazing circuits, doesn't really have such a legendary track with so much history and held in the highest regard by every car nut in the world. So people, rightly so, admire it. Plus add the fact that 80% of car manufacturers develop chassis/handling-characteristics of sports cars there, well not many places in the world comes close. Plus where else would you find such an amazing track so accessible to anyone wanting to try it out?