When I get in the shower, first I wash my hair, then I put some conditioner in. After that I use a facial cleanser for my face, and then a beard cleanser. Then after all that I use one body wash for everything else.
It seems like there's a big market being missed out by specifying more parts of the body. Surely the bottom of your feet can't be cleaned perfectly by the same product that you use for your nipples. I can imagine a bottom of the foot wash, a leg wash, a ball wash, a penis wash, a pubic hair wash, a belly wash, and a backwash. And of course a butt wash.
Of course this would be terrible for the environment as the amount of time you would spend in the shower would be extraordinary. Still though, I can see something like this eventually happening, I remember when the two-bladed razor was introduced, followed by the three-blade and then the four-blade versions and I don't even know what it's up to now but I don't think any of them are much better than the one.
Then you have the two-in-one conditioner and shampoo, which seems like a paradox to me. Isn't shampoo meant to get the kind of thing that conditioner is out of your hair? But who knows, maybe some brilliant scientists in the future will come up with The one for all wash, perfectly optimized for every single part of your body.