You're right, a nicer frame would probably make for a better ride. Cost is obviously factor, but a bigger one for me is that I want a bike that I don't have to treat like it's made of glass. One of the things I really like about my too-small Sports is that the paint is thoroughly beat up and chipped, the chainstays are squashed where someone overtightened the kickstand, etc. I didn't have to worry about riding it through mud, road salt, and over bad dirt roads that send little sharp pieces of gravel pinging off the frame. I've got enough bikes that I have to keep clean and pristine.