We often see people complaining about how some UIs on various OSes or softwares haven't changed in years but, in a lot of cases, it's just that once you've found the most clean, simple and obvious way to make a UI element/menu/etc., why would you ever change it?
I mean, there's a huge lot of objects in our everyday life that haven't seen change in their basic shape since...their very invention, and nobody would have the idea of changing that. Why should it be different for softwares?