This is not in any way meant as a refutation to your point, but merely as a "for your interest" piece of information:

From working in the TV industry, I can tell you that real money comes from sports broadcasts, which also means that the sports people are the ones with money to burn. Apparently, ESPN made an attempt at a TV channel dedicated to 3D broadcasts of sports events. It was discontinued in September last year not for lack of content, but because of the reasons that you dismiss :) (See http://en.wikipedia.org/wiki/ESPN_3D ) Similarly, I expect early 4k TV content to be sports and news.

So, movies isn't the only kind of content and 3D TV channels have failed because of lack of adoption. This, however, doesn't mean that lack of (even more) content still isn't the cause of lack of adoption.