I would use the dual pixels for a more compact RGBG pixel layout with better colour accuracy, but that's just halfway to increasing resolution by 4 times and getting a perfect RGB signal per pixel (counting four photosites as one pixel).
It would be nice if camera companies would just switch to the same standards as display companies use and count groupings of three sub-pixels as one pixel.
Nice idea, but that's presuming you want to display the image on screen at 1:1 using a current generation display. The problem is people print, people display at other sizes than 1:1, and display technology changes. Compare colour CRT's with their seemingly unrelated pixel and RGB layout, LCD's with predictable pixel to RGB layout, pentile displays etc.
Take video for example. Rolling shutter is a very real problem, but roll back the clock to the very first video camera and TV - a one pixel camera with a spinning Nipkow disk
. It had zero rolling shutter because the display device was a single light lit by the electrical output of the single pixel, and another Nipkow disk. Great system, but only good when matched with a specific output system.
The best is surely to get the recorded image as close to theoretically perfect as possible, then as output devices mature (by chasing that same goal), it all looks good regardless. However, with retina displays, high DPI printers and high MP cameras most of us have within reach now, the detailed arrangement of how prime colours are individually captured and reproduced has become almost meaningless.