We were able to see available rooms on deck 8 for the August 15 cruise. I am thinking maybe it is just sold out on other cruises?
We are also a family of 5 so per
@GoofyDisneyDaddy maybe that is why we were able to see it. With so many families who want a murphy bed even though they don't have 5 people (e.g., 3 adults not wanting to share a bed; parties of 4 who don't want to climb up the bunk; 2 adults 1 kid and want to leave the couch down at night and naptime for TV watching) it may be they held back that floor to ensure travel parties of 5 had rooms they could book.
I note deck 8 has a massive laundry center in the middle so I would personally steer clear of midship there. The laundry rooms on the other ships are much smaller and spread out on different floors and even then, they were always such a zoo with people queuing up in the hall and coming by early morning to get the machines first thing. Not to mention saw some nastry arguments when people didn't pick up their laundry right away. Can't imagine it would be super quiet/peaceful with a single enormous laundry for the whole ship next door.