Can't agree, I'm afraid. It's easily the most important station on the Surrey stretch between Reigate and Guildford and is well used (with ticket sales data being possibly misleading). As well as the town of Dorking itself, it offers an interchange with a north-south route and several bus routes. It's also doubtful if the faster journey would be of any real benefit given the apparent difficulty of fitting it into the paths en route.
The logic of missing out Dorking is that it is the smallest station on the new "very fast" train, and officially equal in users to North Camp and Blackwater which are skipped. But I take your point that unofficial numbers may be higher. In my experience seems to be mainly under 25s alighting there!
On diesel, It’s worse than the existing stock.
Uh-oh. That doesn't bode well for keeping the same timetable. It would have to be very strong on the 3rd rail sections to make up the difference.
One advantage not discussed much is interior noise. I do find the current stock a bit noisy as a passenger so hopefully the 769s will improve on that.