Commercial systems operate under constraints that Linux didn't have until recently, such as needing to maintain backwards compatibility. This went all the way from not changing the interface for people who used workstations for highly skilled works but were not "geeks" (e.g. CAD guys), to sticking with old shells (e.g. Sun stuck with ksh long after Linux had bash). Witness the furore over the GNOME team changing things a couple of weeks ago...