The $190 also covers Magical Express transportation from the airport, which has some value if you are flying in.
The $190 fee does not give an exchange guest anything that someone staying on an owner's points would not get, with one exception: the ability to call DVC Member Services directly rather than have the owner have to do it on your behalf. It's a nuisance fee, and nothing more.
Granted, I pay it when I stay there, because I believe the overall stay is worth it. I am unlikely to do that for the Orlando or Vegas HGVCs, or nearly any Diamond resort---in those cases, there is no reason not to take an exchange at an equivalently-nice alternative in the area. I would be willing to pay it for the Ohahu HGVCs, and might for the Waikoloa resorts depending on the situation.