[CentOS] group install KDE does not enable runtime?

In my continuing investigation of CentOS-7 I did yet another minimal install. Subsequent to that I ran yum update kernel, and then yum group install KDE.

Now, KDE installed about 480Mb of stuff, which compares favourably to Gnome's 971Mb. However, when I run startx from the command line, instead of getting a desktop I see these errors instead:

xauth: file /root/.serverauth.12462 does not exist

xinit: unable to run server "/usr/bin/X": No such file or directory

Followed by instructions on how to link "/usr/bin/X" to ones choice of display server. This seems a little awkward for a mature distro. Is it really the case that one must hand link files to get any other desktop instead of gnome? is this by design?