I think so too. Public networks are networks full of hackers and NSA agents. The VPN-like protocol should be built into device so it doesn't accepts any packets

I think so too. Public networks are networks full of hackers and NSA agents. The VPN-like protocol should be built into device so it doesn't accepts any packets not coming from its home network. And VPN (unlike SSL) allows encrypting traffic for external obverver while keeping it plaintext for owner.