To be honest, I still don’t get what is good about UPnP, but I see how bad for security it can be. ;)
Also, in enterprise and carrier networks it has no use anyway. So I’m not sure if it should be included by default, but we’ll see. I see no reason not to include it into an addon repo though.
If you want UPnP right now, you can pick the package from EdgeOS source tarball, rebuild and install.