That does seem to be an accurate name, it is a feature that's offered and up to the site operator to enable, and yes it's unfortunate that it potentially gives a false sense of security to end users. However in almost every case, it's still better than both sides of the connection being unsecured.
I'm not sure what this has to do with all CDNs being MITM operators when caching secure content.
At the very least, Cloudflare should do a better job of discouraging use of Flexible SSL. People that opt in to Flexible SSL should know what they are doing.
I'm not sure what this has to do with all CDNs being MITM operators when caching secure content.