Much of the work done by licensed "professional" engineers requires knowledge obtained through a rigorous accredited academic program and years (usually about four) as an apprentice under a licensed engineer. The knowledge needed to accomplish an engineered project is considerable. The knowledge runs the gamut from pure deductive science to arcane codes designed by experience all woven together in a complex of ideas sometimes at odds with one another. The risks to the public for inept engineered work is great. Buildings could collapse, electrical systems can explode, dams can break open, waterworks could acquire fatal bacteria, and so on. The engineer must balance the safety of the public against the cost to provide that safety. The role of the modern professional engineer is certainly in accord with the modern use of the word engineer:
to plan, manage, and put through by skillful acts or contrivance; maneuver. But the modern professional engineer who is licensed by approved state organizations is an outgrowth of the traditional engineer who evolved out military engineers who had their beginnings in Roman military engineering that organized and built much or the great Roman infrastructure.
One distinction that should be understood is the professional engineer is personally libel for defective work. This is in stark contrast to computer programmers and other technical professionals who engineer their work. When your operating system crashes do you sue the programmer or do you sue the Microsoft? Until programmers take personal liability for their work, they should not be counted among the Professional Engineers
You hit the nail on the head. Responsibility for designing crappy code is virtually painless!