Follow the money.
It was designed that way so that less and less people can fix and maintain their own vehicles. It was designed that way so that people have to take the vehicle back to the dealer for repairs and service.
One small example is the three trucks I have owned in the last 22 years. All Dodge (now Ram) all with a Cummins diesel. The 2001 model was very easy to maintain. Fuel and oil filters were very easy to get to. The 2008 model, the oil filter was very easy to get to, but the fuel filter was a bit of a pain. The 2016 model, I currently have, has three fuel filters, one at the tank, one on the firewall, and one above the frame behind the front driver side tire. The firewall filter requires a ladder beside the fender to get to. The frame filter requires going between the frame and inner fender.
The oil filter takes the cake though. You cannot get to it from beneath. The 4WD front end completely obscures it. You cannot get to it from above. The ail cleaner, A/C lines and alternator almost obscure it. You get to it via the inner fender and frame from the passenger side front wheel. You have to tilt it horizontal to get it out, dumping black engine oil on the front end and on the floor. No other way around it.
For decades, the Ford Powerstroke has certain procedures to correct engine problems that require removal of the entire cab of the truck. That makes those procedures very expensive.
Follow the money.
