I guess that many things would improve if the target audience for the motorhomes were asked by manufacturers what they want. I know it is all a compromise in terms of how people use the van but a few surveys with modest prizes would help to create the image that someone cares.
They also have the knowledge from faults, problems and leaks to build out the previous problems but model after model turn out with leaks. If this was not the case there would not be so much emphasis on damp testing on the Habitation service and trade ins.
For me a few bits of trunking with draw strings in them would make the addition of Sat TVs, Solar Panels, extra LED lights, alarm systems, extra Power sockets both 12v and mains, so much easier and cheaper.