You'd be surprised. Just listen to the arguments against giving Linux a more logical directory setup (somewhat like OS X's).
Personally, I think the various flavors of directory setup are already so divergent that tradition no longer holds massive value, but that's not something to be proud of.
The problem is the comparison point.
When original Gtk/Gnome came out, it was a WAY worse BPOS than Unity or Gnome 3 are today.
The trick was that when Gtk/Gnome came out there was no existing solution. So, even a bad one was okay.
The problem is that the new solution is competing against an existing solution that has more than a decade of development behind it.
It would take a Herculean effort to win that comparison.
There were existing solutions, e.g. Motif or Athena widgets if you wanted a GUI library, or FVWM if you wanted a desktop environment. Of course, GTK/GNOME was a significant improvement.
Qt and Gtk were a breath of fresh air. And Qt got everybody's dander up due to 1) license and 2) C++ requirement.
So, Gtk basically stepped into a vacuum.
At least for Unity and Gnome 3 (including GTK3) I'd rather say: Great ideas but they're evil because they are badly designed, full of bugs that don't get fixed due to complexity, constant API changes, almost no documentation or only wrong and outdated documentation and a lack of flexibility that annoys even the casual Desktop user.
Nobody is against progress - most people love to use OS X as a UNIX GUI these days... it's not perfect but it's not that bug ridden mess GNOME became.