Aesthetics is a mostly subjective matter. But if the lack of ribs bothers, then an intelligent gunmaker would contrive a removable rib satisfying aesthetics while giving access to the space between the barrels. A removable carbon fiber rib weighs less than 30 grams, Benelli uses them on some models, they are adaptable to double gun construction.
Alternatively there is the Darne tactic of using only a top rib, thus saving weight while providing access to the barrels.
To cure this rib thing watch a rib relaying process and see the rust and pitting in between the barrels. Dewey Vicknair has some photos on his site.
And no, tinning is not a sure way to prevent between the barrels rust. Rib relaying ruins the bluing, thus for the sake of one single square inch of solder surface area (maybe even less) one pays the cost of total reblue. Sounds kind of backward but to each his own.
