Customers who don't need a GUI may create a custom Revolution Pi image based on "Raspbian Lite" using our imagebakery scripts: https://github.com/RevolutionPi/imagebakery
I would suspect it would be more common to connect via ethernet from a PC or laptop, vs local console. Especially for field servicing, carrying a laptop is simpler.
In the case HMI is needed, installing the desktop is just some additional packages.
This raises another question: what repository are you using? How are (security) updates handled, if at all?
Since the image is based on Raspbian, updates are installed via apt-get as usual. There are some deb packages of our own pre-installed. Updates for those are made available via our apt repository at packages.revolutionpi.de.