Why not three rows of four, or two rows of six, or turned upside down like a calculator keypad? The key arrangement would be the smallest, cheapest and easiest thing to change.

But that would break users' dialing habits. It would slow them down. Eventually, they'd trash that oddball cell phone for one that isn't such a pain to use -- one with a regular set of keys.

Your car's speedometer probably has an indicator that moves from left to right (or, if it's circular, moves clockwise) to tell you you're speeding up. That's the way it's been for decades, though nearly everything else in the instrument panel has changed. Why not right to left or counterclockwise? Because that small shift would break drivers' critical ability to read the speedometer.

Kitchen sinks in the U.S. have hot water on the left and cold on the right. That's true whether you run water by twisting faucet handles, pulling a knob or moving a joystick-like lever. It doesn't have to be. But anyone who's ever been scalded by plumbing set up the opposite way knows why left hot/right cold is a valuable standard.

Now let's talk about users. What drives them nuts about new systems? Broken habits. Users can take major process changes in stride. But keyboard shortcuts that no longer work, buttons that no longer do what users expect, defaults that have changed -- they all create errors when users try to keep working the same old way on new software or hardware. And if the systems can't be adjusted to accommodate users' habits, the habits have to go.