HTTP is a cleartext protocol. Why does your browser quietly navigate to any HTTP site you throw at it? Anonymous FTP isn't any less secure than HTTP.
Why does your browser scream at you for connecting to an encrypted but unverified site, such as a self signed certificate on a closed network, but have no warnings at all for an unverified and unencrypted HTTP connection?
How do you know the context that I am using a plaintext protocol in? How do you know I'm not connecting over a patch cable to the computer next to me? How do you know I'm not connecting over an SSH tunnel?
The user should easily be able to override these safety measures.
The only argument I have heard this is that the user could be tricked into disabling security mechanisms. But that is true of anything in computing. The user could be tricked into typing in rm -rf.
When there is inconstancy like this, it usually implies there is something else going on that we aren't seeing. I have a feeling that companies like Google and Apple have an agenda to move people away from having too much outside of their influence.