1. It seemed too heavy for the powertrain (at the time, I believe the largest engine offered on it was a small V-6).
2. I never liked the idea of building an SUV on a pickup truck chassis. Not enough leg room inside (especially in the back seat).
Until recently, most SUVs were built on pickup frames. It adds great strength and allows them to go offroad and not break. (Note that the FJ Cruiser, a Toyota unibody, is having body cracking problems when used offroad.)
That said, lack of legroom is not a function of whether it’s unibody or body-on-frame but of interior design. Case in point is my 90 Nissan Pathfinder - tons of room in the front; my 7’ tall basketball player friend fit inside just fine. Rear legroom is OK - if the front seaters aren’t basketball players and don’t have the seat back all the way. They did fix that later with the next generation of Pathfinder and XTerra.