That's rediculous. You're recommending that people stick with old versions that are riddled with known vulnerabilities. There are some great lightweight modern OS's, like CrunchBang and Lubuntu that work well on old hardware.
I think you're missing the point. It's common practice to sunset something. Apple, Google, Microsoft do it all the time. The fact is the support for some version of OSX has been deprecated and not supported any more. What are those folk to do?
Ubuntu 12.04, which has a version of Gnome classic, is still supported until 2017 (https://wiki.ubuntu.com/Releases). If someone is running hardware past this date, well, they are going to be on their own. That's life. That's software.
Just to be clear: you think it's preferable that people using old hardware should run old Ubuntu-with-Gnome and accept their known security holes, than that they should use still-supported, modern OSes designed to run on old hardware? Did CrunchBang run over your dog?