IPv4 is simple, we all love it and have gotten used to it. We love it so much that we are spending so much time to develop ways to keep it around as we fight the impending doom of IPv6. We all know it is going to happen and in many ways it already has. Developed are our home systems and Gateways that can translate IPv6 as IPv4 and stand as IPv6 and direct to IPv4.
While IPv4 has around 3.4 Billion addresses it is capable of, comparing that number to the total amount of people on our planet Earth, 8 Billion and that grows at a rate of around 0.87% or 71 Million people annually, being able to keep IPv4 around this long is an achievement! Developing features like Port Forwarding and NAT (Network Address Translation) have been a great help in keeping IPv4 around.
Hopefully, we figure out a way to keep IPv4 for private networks and use IPv6 for public networks and not have to worry about the change from home as much.