Can we go back in time and hit the designers of IPv6 upside the head? The decision not to make IPv6 backwards compatible, the belief that a beautiful new standard could magically replace something already so widespread... "Naive" is an inadequate word. We are still futzing with the transition 3 decades later, with no end in sight. Grrr, grumble...
But the biggest problems of all: You can write an IPv4 address on a phone call. You might be even able to remember it. Not the case for IPv6, you need to be an expert in Hex and remember the specs design. I can't do it as a developer, I don't think normal people will be able to do it either.
IPv4 is useful because it's just a number (at least from a person's perspective). It works. Just add a letter to it and then you have x26 the capacity.