I have to agree. With the paint process that manufactures use today you should need nothing more than to keep it washed and give it a wax every six months or so. To be totally honest, if you do the wash my hand use a combination of wash/wax cleaner and your done. Or even the spray wax at the local car wash will keep a protection layer of shine in place.
Dealers have been pushing the same aftermarket interior/exterior protection products for years. Why do they do it, because it is a very high profit margin product.
Now if they come out with a aftermarket exterior protection that is strong enough to door dings, scratches and scrapes it would be a different story.