Usability expert Don Norman wonders why we build things that confuse the people who use them:
Answer: Because the people want the features. Because simplicity is a myth whose time has past (sic), if it ever existed.
Make it simple and people won't buy. Given a choice, they will take the item that does more. Features win over simplicity, even when people realize that it is accompanied by more complexity. You do it too, I bet. Haven't you ever compared two products side by side, comparing the features of each, preferring the one that did more? Why shame on you, you are behaving, well, behaving like a normal person.
Norman focuses on toasters and fridges etc, but Joel Spolsky takes up the baton for software. applications:
With six years of experience running my own software company I can tell you that nothing we have ever done at Fog Creek has increased our revenue more than releasing a new version with more features. Nothing. The flow to our bottom line from new versions with new features is absolutely undeniable. It's like gravity. When we tried Google ads, when we implemented various affiliate schemes, or when an article about FogBugz appears in the press, we could barely see the effect on the bottom line. When a new version comes out with new features, we see a sudden, undeniable, substantial, and permanent increase in revenue.