Back in the 80s, station wagons were losing selling power. Chrysler took a station wagon and raised the roof and bam the minivan was born!
As for the SUV, it used to be a truck to haul people (think suburban and power wagon). They were rugged so "the boys" could go huntin and not have to ride in a truck bed. Jeep, Land Rover, Toyota, etc., all started making a version. Truck to haul people.
In the 80s, the SUV became a more stylish version of a minivan. People liked being able to carry 6-8 people while still having an appearance of being "withit". This was when the modern Jeep Cherokee came into being.
By the late 90s, manufacturers started shrinking the SUV. These are what we really consider crossovers - they only hold 4-5 people and have lower roofs. They are the new station wagon. Mom and Dad up front, 2.5 kids in back, and space for groceries, etc.
By the way, the Durango started as body on frame, then went to unibody, and is now back to body on frame.