Wouldn’t that be far more efficient and effective?
No, it would not be more efficient. The cost of a camera such as the one cited, not to mention storage of the massive output of data is certainly not efficient compared to still cameras capable of the same resolution.
No, it would not be more effective. Video is shot to look best at dozens or more frames per second, and video cameras are designed to shoot for video, not for still frame grabs. In order to make the video look smooth, longer exposure times are used that cause individual frames to often show motion blur. Our brains compensate for this when watching videos or motion picture films. Not so much when looking at still frames captured from motion pictures or video.
What am I missing?
The hours and hours spent looking at each of tens of thousands of frames to cull them to the "best" ones?
The massive amounts of data to be processed and stored?
The differences between high quality video and high quality still images?
The use of flashes and modifiers to create photos that would be highly impractical if not impossible to produce using continuous lighting and video frame grabs?
Beyond all of that, the best photographs are very often those that are carefully calculated to capture a specific instant in time. Careful thought and consideration goes into the various compositional elements of a scene and the lighting. Shooting video at 60 fps and saying, "I'll find the best composition and lighting by looking through thousands of more randomly captured frames" isn't very efficient nor as effective as using a still camera set up to shoot stills and used by a skilled photographer. Rather, it seems to be the ultimate example of spraying and praying.
While it is true that motion pictures can do the same kinds of careful planning, executing such plans at 24 fps can get quite expensive in a hurry. Massive amounts of lighting and modifiers are needed, and a small army of electricians and grips are needed to set up and operate them as the actors and/or the camera moves during footage capture.