I stated specifically that I agree it is bad in situations where you could be MITM. I also agree many people do that. My question here is only how it could effect me or people who follow the practice I follow.
Your assumption that there is such a thing as a "secure network" is foolish. ISPs inject vulnerable javascript into pages, ISPs have vulnerable routers, ISPs have bad passwords on their devices, ISPs have criminals on staff, ISPs run traffic through unencrypted microwave links that anyone close to the beam can listen in to, ISPs have devices running in remote locations, ... and your traffic is going to run through who knows how many ISPs, possibly even through other countries, ... in short, it simply doesn't make sense to build anything on the assumption that the network is secure.
