"As I understand it the critical factor isn't emissions but crash safety for pedestrians. "
It's all round safety. Range Rovers and Land Rovers are mostly exempt from EU crash safety requirements as the chassis are virtually unchanged from initial production, long before those regulations came into effect all those years ago.
Pedestrian safety is affected by the externals, so that's what's driving the runout of the range - changes necessary to comply with that mean chassis changes and that in turn means the grandfathering goes away.
On top of that, Defenders/90/110/Serieswhatever haven't been road legal in North America since 1993, so that's a large chunk of the market they're locked out of (even before then, North American units had to have a roll cage integrated to be able to be sold.)
In the real world such grandfathering should have only been allowed to continue for 3-4 years at most.
The last LR I had to put up with was a series 2 back in the early 80s. Compared to Nissan's Patrol and Toyota's Landcruiser it was atrocious (Shocking on-road handling, unreliable electrics, gutless, thirsty, high maintenance and couldn't handle conditions in NZ mountains in winter that the other two didn't have trouble with) so I was glad to see the back of it as a work wagon.
I gather they improved a lot after that but the damage had already been done ("Made in Britain" was already regarded as a warning label in the 1970s, but government directives mean that many organisations ended up buying british machinery long after the vast superiority of japanese-sourced stuff was apparent to everyone).