Sorry, but I cannot agree.
I had my Honda treated with "sureguard" before I took delivery and it is excellent. The dirt literally falls off when the car is washed and the deep shine is brilliant.The inside of the car is also easy to clean as the dirt does not get into the upholstery or carpets.
My wife had her Clio treated with "V V P" by the dealer and this is also very good. Black is not an easy colour to finish well but all it needs is a wash and chamois to get good results.
I would agree that the treatment is not cheap but I think that relative to the cost of a new vehicle it is a small extra that I think is well worth it.