They sound really dumb, right? Really bouncy and hard to turn...
But square tires work PERFECTLY on roads that are shaped like this:
(Well, those bumps should all be equal sizes and correspond with the size of the square tires, but if it WAS all perfect, the bike would ride perfectly smooth. I'm free-handing this in Paint, after all...)
So I guess you can apply this to other things in life. Sometimes it isn't the tire that's the problem; maybe it's just the road. Also, every shape of tire has a road that it can ride perfectly smooth on. No kidding. Try drawing a road for an ellipse.