"Because the name “Land Rover” conjures up images of Defenders, Series vehicles, farmers, Camel Trophy, rough 4×4, working class, winching through mud."
This isn't true for the US market, and if I had to guess: probably not for the Chinese market either. The US sees Land Rover as a lifestyle brand - kind of cool and sporty but upper-middle class and suburban.
I think this has more to do with differentiating the different models (Defender/Discovery/Range Rover) and keeping the branding as simple as possible. (I still think it's a mistake and will dilute the brand.)