IMO people make a huge deal on the whole body on frame thing, but honestly it isn't nessacery to have that and still get all the off-road chops people desire. BOF is important for trucks, with beds that require big payloads, not as important for an SUV. I for one am fine is they go to unibody, and I know this is an unpopular opinion, but would maybe prefer it.
The BOF thing is important in the context of a utility vehicle. Mainly for having somewhere to bolt to that's robust. It's certainly possible to do with a unibody as well, but typical unibodies aren't really designed to handle external forces well. For example I have a snow plow I use all winter on my 4Runner. I've yet to see a viable way to put a snow plow on most unibody SUVs. A tube frame UTV is a unibody in a sense and they have some ways to do it. It's not impossible, but it's really uncommon.
The other consideration is that unibody doesn't necessarily have any weight advantage. Compare a Tacoma to a Ridgeline. The Ridgeline is heavier. The Highlander is around 400lbs lighter than a 4Runner. But they're nearly identical in size. All you need to do is correct for the difference in wheels/tires, axles, and the transfer case, and they're damn near identical in weight. The unibody design has advantages in interior layout, but it really doesn't do much or anything meaningful for weight savings. The 2020 Land Rover Defender weights more than the 4Runner. And it's mostly aluminum. The Jeep GC weights the same as a 4Runner.
Solid axles have significant advantages in terms of load distribution. This is a copy of my post in another thread that probably helps explain it a bit:
In a simple scenario where you have a 72" track width and springs with a constant rate mounted inboard at 48" width (1 foot in from each WMS), and a spring rate of 200lb/in and the axle is bearing the weight of 2500lb. On a level surface each tire is loaded with 1,250lb of weight.
Now let's assume an obstacle where frame remains level and one tire is on top of a 12" rock. So the axle system will be put at a 9.56* angle.
With a solid axle modeled as a continuous beam with two point loads (springs) and supported ends (tires) the force on the tire displaced upward will be 1783lb and the force on the down side will be 717 lbs. (The springs will be displaced 4" up on one side and 4" down on the other, but that does not calculate the ground force distribution which will be a more complex, but not terribly complex, beam with asymmetrical point loads).
With independent suspension modeled as two independent systems attached to the frame without a cross suspension link (like KDSS) the force on the upper tire will be 2450lb and the lower tire will be 50lb.
For me and my use as both an offroad adventure vehicle and a daily driver, I think the compromise of IFS and solid rear axle is ideal. I would prefer that over either solid front and rear axles or IFS/IRS. It's the balance that best fits my use. So for me the new bronco is just right in that respect. I want a truck with extra seats moreso than a car with big tires.
