Everything is made-up and nothing has to be the way it is. Everything is this because people decide this is.
Ever read "The design of everyday things" by Don Norman?
Drove this idea home in incredibly detailed and interesting ways.
Sadly we get entrenched in those ideas and forget. I think it's a side artifact of our being creatures that learn by mimicking and modelling. We get into a pattern, assume it's the one true way and it becomes a rut.