The huge advantage of nano over vi in that scenario, is that nano 1) uses the conventional [i.e. as used by every editor other than vi] arrow key cursor movement and typing behavior without the need to toggle any modes etc, and 2) displays the shortcuts you need for anything else on the screen by default - things like saving, cutting/pasting, searching, and, oh yes, quitting.

So, while it might not be optimal for vi users, it is at least accessible to pretty much everyone regardless of their background. Whereas for someone not familiar to vi, getting thrown into the dreaded : prompt can be a frustrating nightmare.