You know, .... they hide extra "spaces" so you won't overload the camper!.... remember "The Long, Long Trailer" movie? Lucy stowed away all those rocks in every storage space available? If you can't access them ... you can't stow anything in them. .... sounds logical to me anyway! :h
Still, in my camper I have areas that could be better utilized too, if I had a real need for more storage: There's space above and below the refrigerator, behind the microwave, the space where the trailer power cord comes through the outside wall, under the shower pan (really, there an access panel on the front of the shower pan, and that cavity under the shower pan is huge!). Space behind the oven (although it might be hard to get to).
Not to mention all that empty space outside, especially that space between the two main trailer frames that could be used for a LOT of stuff.
But, then ... if all that space was used ... I might find myself wondering why my poor truck is screaming and blowing smoke like a burning tire factory!