I actually have stayed in a hotel (Pod 51 in NYC) as recently as this January that had shared bathrooms in the hall. Everything was clean, the room was small (even by Manhattan standards), but I paid less than $80 a night. I've stayed in any kind of accommodation that came with a private unenclosed toilet in the room. Other than Viewliners the only other modern accommodations set up like that are prison cells. I've stayed in other micro hotels that bathrooms, but the toilet & shower were still in an enclosed cubical.
Sleeping cars are an extremely tight squeeze and shared facilities make more sense when trying to fit as many revenue spaces in as you can and still give everyone a bed. And the Viewliner II's still have options for passengers who want en-suite facilities. Even on airlines with First Class "suites" passengers still share bathrooms.