Self-reinforcing arms race to sit up high and see over the top of traffic. If people could be trusted to reliably signal, merge, etc. the perceived need to see 300 feet ahead to predict behavior of immediately adjacent drivers would diminish.

They're not really back. Station wagons have just grown into them to compensate for the compromises in features that modern sedans have suffered in the name of fuel economy and safety.

People want something that's AWD, has a belt-line lower than your nose and a trunk that's integrated with the rest of the cab. In order to get that in a package that meets modern safety requirements it needs to be decently big and decently heavy. To make a decently big and decently heave vehicle comply with modern fuel economy and emissions rules you have to be able to call it an SUV with a straight face. Enter the "crossover".

Sedans and compact hatches make great commuter cars but if you can only afford one payment at a time then you can only really justify buying a multi-tool of a vehicle. On the small end that gives us things like the HRV. On the large end that gives us crew cab pickups.

SUVs were a thing during the Reagan years. Although they were mostly 2 doors and based on small pickups with body on frame construction and very little power by today's standards.

In 1987 I remember you could get a 4Runner, a Pathfinder, a Cherokee, a Blazer, or a Bronco.