Because the features that make it superior to one person are not demonstrably superior to another. Bigger and more detailed isn't necessarily better.
Why do I use my cell phone, which has an address book, and calls people, and that's all it does? I could instead for no additional money have a cell phone that takes pictures, keeps a calendar, checks my e-mail, and plays games. But I don't need it. All the extra features, while nice, get in the way when I want to simply PLACE A CALL. I have to scroll through three other options if all I want to do is dial a number. It'd be nice to buy new batteries for my simplistic phone, if they made them; but they don't.
Any more sense, or is the example useless?