But what do you do when you're in front of a machine that doesn't yet have a network connection?
Or what if you're onsite with a client who doesn't have emacs installed and doesn't want you connecting to anything outside his network, much less installing any new packages on his machines?
These are quite common scenarios for many sysadmins. And in either of them you'd be screwed without at least a working knowledge of vi.
Don't get me wrong, emacs and TRAMP are great! They're just not always available when a sysadmin needs them.