I'm just taking a guess but I'd say the EPA had more to do with it than GM's marketing and design departments. They had to meet the emission and fuel standards. That ruined many a good vehicle including pick ups. I drove pick ups from the early 70's up through the last one I bought an 85. All of them I could crawl into the engine compartment, sit on the wheel well, and change plugs etc.
My dad left me his 95 F-150 three years ago. I changed the plugs and wires on it and was standing on my head from a step ladder trying to reach them. The old trucks four grown men could fit in the cab and be a little crowded. The 95 two grown men and a 20 pound dog will take up the front seat. All that just to meet EPA standards.
Used to drive a 69 GMC pick up.
That thing was a mule.