I also believe that trading real networks for supposed security would be a very bad move.

Network node security should not be delegated to the network. Not only would this necessitate forgoing very useful features that networks enable, you won't improve node security. Devices that are vulnerable by merely sharing a network with other nodes tend to have other more sever security lapses.

I agree that a button is simple way to switch between modes, but it will also make point-to-point the default. People don't change defaults, and companies will eventually cease to implement network capability as a result.

I'm all for better network security, but not at the expense of discarding the network itself.