It is not really "not learning", it is more "not learning too much in 1 go", and "not learining too much when you have different versions". I am sure people can learn if you give them time, but usually, you don't give them time. RHEL 7 will come with various news stuff ( systemd is taken for granted, there is story about having xfs by default, and for sure, lots of news other under the hood changes and improvement ), and nowadays, IT is talking about cloud, about puppet/automation, etc, all of them who are rather huge changes since the last few years. So yeah, people can learn, to some extend, there is a limit.
Also, remember we are talking of a default setup. The regular gnome 3 is just 1 click away, this is not forcing anything on people, those that can want or love gnome-shell still have it.