For the love of separation of concerns and other sound software engineering principles I'm against combining a command line RPC client and a GUI server/native client in one executable.
Speaking as a non-developer user I would love to see a complete separation between the two.
It would be awesome to have a server that assumes that it will be managing the wallets of everybody on a LAN and authenticates users via PAM (or whatever they use on Windows to do the same thing) and that the GUI clients were just that and nothing more.
The windows installer could install both the service and the client at the same time so those users wouldn't even know the difference and you could even use zeroconf/avahi to make it easier for the clients to find the local server.