The Install cd (minimal, probably universal too) doesn't have /bin/ed. I find this to be very annoying, because nano is braindead and ex has issues with ed commands.
Yes, and others want vim, and someone would want emacs maybe, or pico or joe or... nano is the default editor, if you dislike it, emerge something else. No point in wasting space on release media to stick every single editor there.
While Jakub was a little less than cordial in his response, he is correct. We aren't taking feature requests for software on the minimal CD. There's a text editor on the CD already.