The problem with some sort of wag bag register is that it would be even more hassle for those that wont use it. You hike in and out without ever needing the bag then you have to go and give it back. And of course there would have to be some kind of nasty drop box that the Rangers would have to fish through and mark off them as returned for people that are going home late.
I once stared at the box of wag bags at the Crabtree Ranger Station junction as I was on my way out to Whitney Portal and decided not to take the bag because I would not need it but only made it a half mile down the trail before a Ranger got really upset that I had not taken one and told me they are mandatory and that I had to take hers out of her pack. Now I am not sure if wagbags actually are mandatory to carry through the Whitney Zone which I doubt but I took it anyway. I think I still have that thing some where.
I think the better solution will come in higher tech bathrooms that can be installed up the mountain. But what that is I don't know. How about when you go it falls into a pit and then is vaporized by solar powered lasers lol.
