practicality, and even beauty.  I'm amazed at how hard it is to find a decent sized kitchen for example.  It seems 95% of homes have tiny, dark, tucked away pocket kitchens that are some kind of after-thought.  "Oh, this home HAS to have a kitchen?  Alright just squeeze it into this closet space right here".

Another example is the massive size of master bedrooms in many newer homes.  This is just a moronic waste of space for a room that is just sleeping quarters for the night, it doesn't need to be 600SF all by itself.

Yet another example is making the garage the focal point of the front of the house instead of the front door.  "Hi, welcome to my garage, thanks for coming over.  Don't worry, we did actually build some living quarters onto the back of our beautiful garage".  This is so, so, so mind-numbingly ugly but so incredibly common.