Yes, please! It would be so much better for local apps that have a management UI at a certain port: for one, you need to find such a free port. That's right, 80

Yes, please! It would be so much better for local apps that have a management UI at a certain port: for one, you need to find such a free port. That's right, 8000, 8008, 8080, 8888, some of those might be taken already ;). In addition you can rely on Unix access control with the socket. Much better than granting access to all local users, such as is the case by default with e.g. Syncthing. OpenSSH can also forward these sockets, so remote use can be safer that way and the port configuration issue is relevant here as well. I've also hoped that NFS and its ilk would be able to transfer Unix domain sockets, but I haven't heard of a system that could do that. Then one could, in principle, just ssh /var/servers/gw over NFS! edit: actually read the proposal and it mentions most of my points, including Syncthing :).