I thought the answer to that is pretty obvious! The results from such tests might let them know that the majority of listeners entering their shop do not prefer the more expensive system, so it would be waste of their money.

Actually as I pointed out it very well could. Such a person may not have even considered that a more affordable system could offer equal, if not preferable sound quality to one costing 10x as much.

A person can not listen to every piece of kit there is, so if they know that the majority of listeners proffered 'A' when personal bias (besides sound preference) has been removed, it is a damn good starting point.

Of course it is not the answer all. What it can provide is a strong pointer in the direction for what the majority of listeners prefer. That information is very useful in all manner of applications.

Why do you find debate of blind testing (and I assume the blind testing itself?) to be about 'invading your pleasures and enjoyment'? The information gained from it can help you find greater pleasure for less money a lot of the time!