The cost of 4K BR discs is an obvious concern. For example, the Clint Eastwood film The Mule is £7.49 on BR, but £24.99 on 4K. OK, you get 4K BR and BR in the same package, but that’s way too expensive. That said, on Amazon today I see that it’s now ~£16. The Fifth Element 4K is £40. That’s stupid money.
To my eyes, DV is way too bright, but where I notice the big improvement is HDR. I’m sure that many people with decent eyesight can see the differences when viewing material in DV, 4K UHD, HDR10/+, etc., and to a degree I can. Going back to HD looks low rent by comparison. A decent player helps. My Panasonic 820 does a reasonable job on both BR and DVDs.
As with all things, early adopters pay a premium. Roll-on 8K ...
Clem