Because manually configuring wireguard tunnels on random devices is a simple task for most people lol. Unifi’s whole stack is all about making powerful tools easier to use for people who don’t want to fuck around with networking.
But you don't need to configure wireguard on the individual devices just on the openwrt router. That's one device and you can keep that on permanently.
Agreed. I use Tailscale (which the gl.inet devices support, because they're basically a pretty front end for OpenWRT, and it supports Tailscale) for my stuff, because I can do it and it's not a real pain to do, but you do have to know a bit at least about networking. This thing looks extremely promising for the "I know this should be possible and I want to do it but have no idea how" level of knowledge as well as the "I want to spend as little time as possible on configuring things" people.