I recall reading an article years ago that stated that to match 35mm film, using reasonably defendable assumptions a digital resolution of around 24 megapixels (plus maybe a bit more) was needed. That seemed to gain reasonable acceptance at the time. If true, then we are only now getting to that with FX cameras although some, like the Nikon D800, are already well beyond it. Of course most people do not actually need that much in practice. I would like it as there is nothing better than being able to look at an image, blow it up and see more, and more, and more detail. But I do not really need it. Besides having this much resolution means that lenses and technique have to be up to it and file sizes are bigger so I then need a faster and more powerful PC to process, plus more storage etc.
I also agree that pixel quality is much more important than pixel number (resolution). I recently bought a D700 with its "measly" 12 megapixel sensor. Its now theoretically outdated technology (such is the pace of change in this game). But boy are those quality pixels! I can shoot in near black conditions at 1600 ASA and there is very little noise, and what there is, is not objectional. If I had to lose that quality in exchange for a 24 megapixel sensor that did not have the quality, then I would not do it. Fortunately sensor quality (and in camera processing software) seems to be getting better too and large file sizes are becoming possible with large resolution sensors. We can have our digital cake and eat it too.