I would like to see mac that does not phone home at all out of box! And if you chose to use internet then it phone home for authentication like icloud.
But for the vast majority of people, a system that warns them their software has been compromised will help keep things secure.
I mean I don't agree with them phoning home for every application startup; they could have implemented it like the https certificate system, where you have a database on your own system with signatures that the OS can check against. They can install the signature (or fetch it) on application installation / update, no additional phone home required. They could even put it in a secure enclave or whatever so that in theory, no malicious software can update it.
I don't think most people can realistically use a Mac (or PC) without ever connecting to the internet.