It is changing.
Canonical's CEO (Mark Shuttleworth) said their aim is to deploy interfaces as good as Apple's.
What do you say about projects like GnomeDo with great interface?
I totally agree and we can name a lot of apps... people, use the software before criticizing!
IMHO yes, there are some OS X apps that are very good in usability but there are a lot of exceptions:
Banshee > iTunes Gnome-do > Quicksilver (even though this is not from Apple) Nautilus > Finder (yes this is very true)
I'm not even mentioning the apps that just don't exist in OS X: a real multi-desktop, Tomboy (even though there is a port), a real app manager.
This won't change.