Because words sell, not graphics. If you have any doubts, try this simple experiment. Even if you miss, you'll land among the stars. But, in the US, competition, the lack of a single dominant wireless terminal, and pure Yankee ingenuity has created a plethora of wireless terminals. Now that I m living in Finland, I realize that the US is not really behind in wireless, just following a different path.
Report touches upon a few principles of quantum physics.
So design with visibility in mind. Visitors should be able to find your site in search engines, bookmark its pertinent pages, and forward those pages to their friends. Frames can interfere with these goals without your knowing it. The wireless business is futile if you know technology but don't know what your customers want. Most studies bear this out.