Not sure how or why we would try to prevent utter stupidity! I am firmly against forcing uses in any direction.
Please just make it easy to switch back.
A root login on X is not nessaccary, in no situation (except the design of your installation is crap or you switch to init S and you have password based login enabled). But it cause big problems if you talk about audit and other nice security and controls. So for what reason should there be a root login in X. It is not even needed in a console. Everything could be done with normal user rights and escalation of privilegies on specific tasks.