A great quote from Joel on Software:

It has been said that design is the art of making choices. When you design a trash can for the corner, you have to make choices between conflicting requirements. It needs to be heavy so it won't blow away. It needs to be light so the trash collector can dump it out. It needs to be large so it can hold a lot of trash. It needs to be small so it doesn't get in peoples' way on the sidewalk. When you are designing, and you try to abdicate your responsibility by forcing the user to decide something, you're probably not doing your job. Someone else will make an easier program that accomplishes the same task with less intrusions, and most users will love it.