It seems you need the accessibility provided by these cabins.
We have booked accessible cabins for years with me just using a cane as I was unable to make the step up into a traditional bathroom and I need the grab bars. It turns out I have had MS for years without a proper dx, but I have had a handicap parking permit throughout this time. We book over a year in advance to get a handicap cabin. Now that we are sailing on larger ships, I am bringing my scooter with me so we definitely need the room. We always use a travel agent when we book.