Most people think good usability is not very important for internal IT systems: you can train the users and write manuals to compensate for bad usability. Also, your internal users have no choice, so they’re not going to go to the competition if your IT system is hard to use.
A story in webwereld shows that this is not true: Politie: onze statistieken zijn onbetrouwbaar. The dutch police are complaining that their statistics are incorrect: they don’t know what is happening, because their employees don’t enter the data. The new system is too hard to use, so employees refuse to use it.
Developers and techies often think that it’s enough for a product to have a specific functionality. That it doesn’t matter if it’s easy to use or not. For example, when a company like Apple launches a new product they’ll go: “that’s not new, some other product had that functionality long ago”. But there’s a huge difference between having a functionality, and making it easy enough so that users will actually start using it. Nice example is branching in version control systems: Subversion has had this ability forever, but Git makes it so easy that people actually start using it.
Moral of the story: usability isn’t just important when it’s a customer facing system, internal applications also need to be user friendly.