Yes I can see that as very annoying, makes you wonder what or who justifies him coming out and talking to a customer.
The way I see it is that forums provide information and knowledge as well as personal, balanced views. Any defects and warranty problems can be discussed and owners/buyers learn a lot about the cars.
A dealer can provide service which can and should get mentioned on here, this can be good or bad. There will be issues that arise and its then down to how they are dealt with.
I am still going through a long drawn out issue with Nissan. My dealer, in the middle of this, has always been more than helpful.
If dealers wish to improve they need to act on feedback, if they dont choose to listen or change then thats their shout.