The 16-GoPro rig isn't for a home user, it's for YouTube channel owners and other video publishers who are making money from their videos and want some more immersive content.
Well I'm sure you'll be able to one day have a rig of 16 RED Epic cameras and crunch through all the 6K videos, but plenty of neat scenes can be recorded with the current version. 16 GoPros aren't cheap (though this could be quite a nice package for a rental shop), but all-in will still be quite a bit cheaper than just one RED Epic body (without lens!).
i don't think you have any idea what you're talking about.
lots of special-interest (cars, outdoors, extreme sports, etc.) youtube channels are filmed primarily on gopro rigs (suction-mounted, body-mounted, drone-mounted, etc.) and they make millions of dollars of revenue.
"professional" means a lot of different things. the content production market is massive and very profitable.
My brother makes professional videos on his phone, as well as a RED camera. It entirely depends on what he's trying to do, and what the people paying for it are looking for.
with a 90 degree FOV (such as oculus) you are looking at the feed from 4 go pros at any moment. the hero 3+ does 4K, so you're reducing four 4K feeds into a single 1080p/2 (oculus DK2) feed.
When you're going from 33 megapixels to 1 megapixel, i'm not sure how much optics is going to matter...
Whereas a home user (who may also want to create such immersive content) is left out in the lurch.