There are several reasons to now be working in 4K. As proven by high definition acceptance, better picture and sound quality will, over time, work itself into being the regular acquisition, editing, and distribution standards. HD took over 12 years to be widely accepted. 4K appears to be on track to gain widespread production and distribution in less than half that time.
By originating in 4K now, producers have the ability to future-proof their investments in the same way that early adopters to HD have extended the commercial value of their programs. Standard definition just doesn't cut it anymore. At some point HD will become less desirable than 4K programming.
From an editorial perspective 4K has opened up new and creative opportunities for re-sizing framing, zooming in images and adding motion to static framings. Where in the past a Producer may choose to use two cameras on an interview they may now choose two distinct framings from one 4K camera, saving dual-camera cost and set-up time.
With the new lightning-fast MacPro's and thunderbolt connectivity 4K is a breeze. Be it colour-grading or editorial, fast and efficient workflows are the new normal.
The cost of acquiring and editing 4K is where the cost of HD was a few years back so budget's don't have to be reworked. The benefits are here for the taking.