Re:
As far as I know the only Range Rovers that have a 2wd option are Evoques, the ones that are 2wd. So not only not proper Range Rovers, but much more like run of the mill quasi 4wds in the first place.
Permanent 4wd, which is often misleading, was the whole point of the Range Rover's and Defender's 'advantage'. When it comes to road use, you rarely have time to react when coming out of a roundabout and hitting a bit of diesel, or swathes of mud at a field entrance, or that frozen stream that is flooding over the windy back road. I constantly feel the 4wd working in these situations to give improved control. I actually prefer the older style switchable systems, as my rule was slow in in 2wd, get stuck, back out in 2wd or 4wd if needed.
Lots of the quasi 4wd vehicles on the road now use clever electronics to improve traction, and have no diff locking, or a very basic central diff lock. They are hugely capable until the snow or mud gets up over their wellies.
Crossing challenging terrain is much more to do with ground clearance and to some extent the ability of the suspension to keep wheels on the ground.
One of the best vans I have had for deeply rutted tracks was my LDV 400. Thanks to the rear double wheels with rear wheel drive and generous ground clearance, it was sensationally capable. We are talking seriously deep rutting in enormous holes. Most vehicles have soft suspension for comfort, and will beach themselves long before their transmission systems are tested.
A set of decent tyres often is all that is needed, and I have driven very deep snow with aggressive tread in older switchable 2/4wds with no bother at all. Series Landies for example.
To be honest, a 5 ton puller, kinetic tow rope and ground anchors is all most need to get a vehicle out of trouble.
4wds are being sold as a lifestyle choice, and most vehicles so equipped tend to be very stiff to get into low ratio if they have it, because they never get used in that mode.
I spend a fair bit of time on 'dodgy' roads, and have been stuck maybe five times in the last two years, and on at least one occasion that was thanks to my stupidity.