Unfortunately. Mac OSX is tied to the devices they are sold on. And Windoze is shipped with just about every pc / laptop sold.. Unfortunately this is marketing dollars at work.

You are right that linux distros typically ship with a gnome or kde theme that clones many features of windows and mac.. but that is for familiarity. I have seen first time users using linux without knowing they were not on windows.. this is a good thing to get acceptance.

Don't be afraid to run with your ideas.. forward thinkers are the ones that change the world!