Take my own example - I'm making reasonable money using an ancient 40D to do events work. This week I delivered some shots to a company who I know will just use these images in newsletters and online. Megapixels are utterly irrelevant in this fairly typical situation - indeed, the client prefers smaller jpgs than the 10MP 40D produces just for ease of sharing and sending!
Where I am losing out is in low light performance - losing shots due to poor ISO quality or to camera shake from longer than ideal exposure times, means my keeper rate is pretty lame. That's why I was holding out for a new (ideally full frame) EOS before upgrading, so a mkIII that promises to improve these qualities over its highly respected predecessor is definitely what I'd like to see.
IMHO, your experience reflects those of most working photographers. I'm far from the best photographer out there, but I'm fortunate enough to earn a living doing this. From a creativity and logistical execution standpoint, I find the low-light and dynamic range limitations of the current crop of DSLRs are far more of hindrance than the sheer number of megapixels that are available. Most pro photogs I know fall into this same category. I think Canon knows this, and geared the 5DIII for this market segment instead of catering to pixel peepers.
Even so, I do acknowledge that the truly bad@ss mofos in this business (commercial photogs, high-end fashion photogs, etc) really do need a ton of resolution. From what I've observed, however, they have so much budget at their disposal that they're already shooting medium format. These are guys with so much budget, a lot of them don't even own their equipment. They just rent out gear, and bill their clients for it. I'm sure the form factor and convenience of a 35mm body would be appealing for them if the resolution and IQ were up to snuff. That said, this elite realm of photography represents such a small percentage of the market that I don't think there's a sense of urgency to prioritize the development of such a product.
That's not to say Canon won't develop a mp monster, but considering the specs of the 1Dx and 5DIII, they obviously felt the bulk of the market wanted all-around performers with great low-light abilities.