My theory, and it's just a theory, is that crossovers and four door pickups have doomed the SUV.
Look at all the people that might be in the market for an SUV. The vast majority are actually in the market for something that drives like a car but with more room for people that isn't a minivan. They couldn't care less if it's body on frame or has true 4WD (or even has 4WD at all), they just want something big that behaves like a car. So crossovers eat up most of that market, because a crossover does what those buyers want better than a traditional SUV does. Then there's a tiny portion of the market that actually want a crossover or a minivan but aren't secure enough in their manhood to be seen driving one, so they pick something like the 4Runner because they like the look (then they come onto forums like this and complain about the ride comfort or a tiny rattle or something and we all point and laugh until they trade it in for something else). Most of the remaining market is folks that want a vehicle with the capability and cargo space of a pickup truck that can seat four or five in comfort, and remember that that's what most SUVs originally were - 4Runners, Broncos, Blazers, Explorers, Pathfinders, etc, all originally based entirely on a pickup with some extra seats, and that's what the original buyers of SUVs were actually after, was something truck based with extra seats. Now the market is full of four door pickups with upscale appointments, and there's no functional difference between an SUV and a four door pickup with a shell, and all those buyers that thought they needed an SUV have discovered that they actually want a four door pickup with a shell.
So you take away those two pieces of the market, and you're left with a very minor fraction of individuals that specifically want a traditional BOF live-axle SUV. The needs of everybody else can be satisfied with a crossover or a four door pickup, so that's what the auto makers are making.