> And if you only occasionally need text editor on a linux server, like when you change some config file or update cronjob and nothing more, nano is perfectly adequate

That's precisely when nano is the least adequate: "sudo -e" or "crontab -e" won't pass the "-w" flag to nano, and without that flag, the automatic hard line wrapping can easily corrupt config files which depend on line breaks for their semantics (a crontab being a great example, where each line is a separate entry).