HD vs. 4K Video resolution questions

I was taking some still photos with my iPhone at 3264 x 2448 for a PP project and it had me thinking. HD video is only 1920 x 1080, which is much less resolution than a basic still shot from an iPhone.

 

1. Why is 1920 x 1080 HD resolution the high quality standard and not 4k video camera resolution? Is this currently a limitation of display devices and price, or is there some other reason?

2. Can I make a 4k still image project in PP based on a resolution of something like 4096 × 2048 and than just downconvert when I’m done? Are there any issues with working with lots of stills of that size in the program?

 

 

Thanks.

via Adobe Community : Popular Discussions – Adobe Premiere Forums http://forums.adobe.com/thread/1082874