If you live in a country rich enough that every ISP customer gets a dedicated IPv4 address you won't see many of the downsides of deploying IPv4 these days. If you don't, you'll get tired of Cloudflare's "checking if your connection is secure" becomes pretty tiring pretty quickly. Even in rich countries, CG-NAT is starting to get used more and more as prices for IP ranges go up. CGNAT also affects people trying to do something silly like "open a port" for a Minecraft server or a VPN back home, which is impossible without a public address.

Outside of CGNAT, just about any protocol works better without standard IPv4 NAT. Xbox and PlayStation have invented their own terminology (what the fuck is a "type 2 NAT" anyway) and have written custom code to work around the different ways in which NAT fucks up your connection. Linux and BSD based routers will do deep packet inspection to figure out if you're trying to do FTP or SIP or H363 and rewrite traffic on the fly while opening holes in the firewall just so you can use basic internet functionality. This has also led to an attack dubbed "NAT slipstreaming" where generations of routers will allow Javascript running in your browser to open any port on your device to the outside, or even any port on any device in your network, despite what your router's firewall may say.

For larger networks (with more than ±250 devices), you get a working connection without having to figure out what a DHCP pool is.

And lastly, while this will probably differ by ISP, my experience is that IPv6 has significantly less latency than IPv4, on the order of 4ms versus 20ms.