Surely the scrappiest room in the villa was for servants, some distant poor relative or rented out to students or what not. I just don't buy that the inhabitants for sure were slaves.
Slaves made up 30-40% of the population so it not unreasonable to conclude that the shabby accommodations would be intended for slaves.
"The webbed bases of the beds were made of ropes"
Does not sound like cheap 79 AD bed to me.
I assumed poor people slept on the floor with whatever coverings they could muster. Suspended beds seem very decadent.
The stretched fabric, like canvas, over a rectangular frame design seems pretty common and would have surely been a more natural early bed. Similarly hammocks - which I thought were common on ships (at least in the later middle ages).
Guess I've discovered I'd like to read a history of beds!