* Having difficulty finding symbols because the keycaps no longer match (I don't know why they don't memorize them after all these years)
* Not knowing what mode the keyboard is in to type one's password.
* Having to use someone else's machine and being startled by the switch, or someone uses their keyboard and switches it back.
* On Windows, in particular, the settings seem to flicker back and forth between Qwerty and Dvorak between programs, and between invocations of the same program. No idea why it's not a global system setting. * Have to reset the keymappings in most video games.
I suppose if you were a full-time typist these inefficiencies would be made up for by the increased comfort of the bulk of your day. But for everyone else -- who spend less than 10% of the time typing English sentences -- the standard is probably easier overall.