Pete, you are hitting on one point of mine, which is the sampling of the market research and the phrasing and presentation of the research questions.
However, I also believe automakers have been working to eliminate demand for manual transmissions. For years not only have automakers been removing manuals from models and engine choices, but not allowing a manual transmission to be configured with completely unrelated equipment. For example, on the Mazda5, you can't get a manual with the touring or the GT. Another case is the Lincoln LS. The V6 only offered a manual, not the V8. Also, despite advertisements, not a single dealer had even one manual LS on the lot, and would not bring one in for me to drive without a non-refundable deposit. This lack of real availability set the manual offering up to failure.
There are two types of demand. There is the demand that people will go out of their way for something. Then there is the demand that people won't. If two cars are on the lot that are the same, one auto and one manual, they'll take the manual. However, they won't special order a car or take another model or different equipment just to get it. It is this second group that would increase the number of manuals sold if they were available for people to conveniently buy.
Colin,
1) I agree automatics are better, however, manual transmissions are not geared to be as efficient as automatics. The automatic often has taller ratios for better fuel economy, making the comparison impossible to make fairly on an apples to apples basis.
2) A DSG still eliminates much of the driving experience of a manual. I would still say it disqualifies than man card as there is no clutch pedal.
3) A manual transmission is easy to learn, and while you were never taught, it is your choice to continue to not learn how. I also believe knowing how to drive a manual transmission should be a requirement for a driver's license.