The ability to use the keyboard as the only main input device is another crossover feature that is used by both the disabled and able-bodied communities, and is part of a debate that is as old as the PC itself--some gamers swear by being ‘mousers,’ while others are just as convinced the only way to play is by using keyboard shortcuts.
For those that have repetitive stress injuries, carpal tunnel syndrome, and muscle or nerve injuries that cause pain when moving joints, the ability to use the keyboard to control the game may be the difference between gaming or not being able to game at all. Going back and forth from the mouse to the keyboard is a nonstarter for these players.
A woman wants to play a brand-new hack and slash game where the point of the game is little more than to run around, kill monsters, and loot new gear. However, the only way to control the character is by clicking on the ground with the mouse. Her repetitive stress injuries make it painful to move the mouse that much. If the game allowed her to rest her hand on the keyboard and use WASD, she would be able to play without pain.