People use beautiful things
In terms of user interfaces, if you want people to use your software it needs to look appealing. Users will stick with a beautiful system that's not behaving much longer than with an ugly system. That gives them a chance to find a successful route through the product.
It doesn't matter how great something's internal design is if no one uses that thing. Of course the inverse applies, a beautiful front end to a non-functioning system is pointless. As with most things, a balance is required.
Biting the hand that feeds IT
