yea, but when water is almost the same price, more effective, easier, quieter, and smaller, why wouldn't you use it? Air still is good, but under 70 degrees isn't that impressive when you can do that with water under 45 degrees.
Not that I do not think that water cooling is a good idea, it is a perfect solution under a certain set of circumstances.
But I cannot see how a water cooling setup is easier or smaller? It may be quieter, but to me anyway, my PC is not all that noisy, does not bother me at all to hear a few fans running. But then, I don't overclock to the extreme either. It takes me all of 15 seconds to install my heatsink, and I bet it doesn't take up near the space a water cooling kit does. Your statement does not make a lot of sense. The vast majority of people do not need water cooling.
I only overclock a little, my fans suite me fine, and I for one do not think that water circulating around inside my case is a good idea when you weigh my needs over what might happen should you spring a leak.
As I said, I am not knocking water cooling at all, it just does not make sense for me, or for the vast majority of people.