I'm not sure where you're getting on par or slightly more expensive. That comparably specced iMac was $3400. Even pairing the Hackintosh with a $1500 5K monitor, you're still looking at $900 additional cost. That's almost another complete Hackintosh build. Go with a 4K monitor and the savings are even greater. There are trade-offs for each decision. As you stated, the iMac would be less hassle and more seemlessly integrated. What you gain in integration, you give up in flexibility, upgrade-ability, and power (grunt).The one issue with that video is that once you make a $1000 PC and pair it with a $1500 monitor, it shows what the value that the iMac really is. Buying a riMac is on par or slightly more expensive, but it is seamlessly integrated.
When I bought my first riMac the only 5K monitors were $2500, so, I saved $500 by buying my 2015 riMac versus building a mackintosh and buying the 5K monitor.
Of course, 5K prices have come down, but at the time, the riMac was the value deal and I think is still apple's best value if the specs work for you.
Disclosure: I don't like iMacs or any AiO's for that matter. I just don't find any value in the AiO form factor. Others do, and I have no issue with it. That being said, the video is primarily about the savings and performance gains over a Mac Pro. This was a build with cheap parts that gave a nice gain in performance. A few more dollars thrown around and the performance potential could even be higher. With nVidia's drivers release, things can get even more interesting. I've built many PC's, but never a hTosh. Might be time since my desired mac mini will be (rumored) some time coming.