Have you even asked them? I don't know too many 18 year olds who would willingly share a double sized sleeper sofa with their 15 year old sister...and vice versa. The sleeper sofas in the villas are queen sized.
Like I suggested, look at some of the videos of the cabins. The bedroom is really tight since Disney switched out the double bed for a queen and the closet is tiny, smaller than the one in a Value and a small dresser. The bed is against the wall on one side, meaning one person will have to crawl over the other to get out. While the renovated living room is an improvement and added more storage, Disney blew it in the kitchen by removing the stove and pantry. And if I remember, the hair dryer is in the bedroom, not the bathroom.
The cabins are not as spacious as a 1 bedroom villa, if that is what you are thinking. The cabins are a moderate, not deluxe resort.