So what happens, say, when you're driving up a main motorway in the middle of winter and as often happens, there's a bank of snow on the edge of the lane and you inadvertently dip a wheel, or theres a little bit of ice across the road.
Your Freelander would naturally distribute power as required when some slip is noticed, but because your car would be stuck in 2wd, you'd be no better off than in an astra and likely to end up facing where you came, or wedged into the car next to you.
Seems like a total waste of time to try and better a system that works perfectly fine when looked after properly. After all, LR only invest millions in R&D every week.