It'd be helpful to have a rest api for system preferences. Currently we use the svc api for a lot of this.
It would be nice to have a REST API endpoint for sysprefs for sure. That said, at the moment the svc/config/systempreferences endpoint only exists on the staff interface. If we added a REST API endpoint, it would be available via both the staff interface and the OPAC. I don't love the idea of people being able to write to sysprefs from the OPAC. Sure, it would be protected by authentication and authorization, but it would increase risks. There are some other security things that we'd want to do before doing this I think.