Built-in furniture could be more difficult to install if you have to make little round cutouts for every piece of pipe or conduit. But the overall effect would be kind of like a naval warship, where everything has to be instantly accessible for damage control. Great if you're homesick for the submarine you served on, but kind of ugly for a camper.
On edit— Having dealt with industrial sites like machine shops, generator houses, and pumping plants all of my career at the Corps of Engineers, exposed plumbing and electrical conduit only makes sense as noted above, where it has to be instantly accessible for quick repair, or on a concrete or stone building where it's just not possible to hide it inside the walls. Otherwise it's better to put it inside the walls where its less susceptible to damage.
Engineering: Finding complex solutions to simple problems you didn't even know you had.