Reading that interview, I do see some merit to the choices made. At the time, the Genesis was starting to pose a real forthcoming threat to the NES in terms of appealing to older demographics looking for something more "adult," more high-tech. The North American design aims for that customer in a similar way to the Genesis/Mega Drive, but in a brighter, arguably less exclusively masculine color scheme? The NA SNES (a lot like the worldwide PS1 design) to me echoes design trends of something like a gray 1990s desktop computer tower. I think between the Genesis/MD, the NA SNES, and the PS1, for the time, all three of the designs successfully helped to sell the idea of a "state-of-the-art" "next generation" device.
It looks like the kind of device that you might expect to play age-agnostic PC ports like SimCity, Populous, or Lemmings (but for a fraction of the price).
I feel like if Barr was worried about the Super Famicom design looking odd when attached to a hypothetical SNES CD or something like a Satellaview, the ridgey bottom of the NA SNES finally makes some sort of design sense if the ridgey bottom of the SNES was supposed to slide seamlessly into the ridgey top of something else. Now, it doesn't look bad per se, but the almost puffy smoothness of the Super Famicom design with a cartridge sticking out sitting on top of the Satellaview does remind me of a bird nesting for some reason if I think about it. (Of course, designing the NA SNES specifically to connect to something else that it never got is a bit of irony)
I will say though, while I love a lot of the Japanese SF box art, the stylish "high-tech" uniformity of the NA box art does -- I think -- hold up especially well. Upon seeing a box on a shelf, you know immediately that it is a Super Nintendo game without it overly diminishing the art and logos for the game itself, and the (not necessarily utilized, depending on the publisher) space on the front cover for a punchy synopsis helped explain to the consumer the contents of an unfamiliar game they were looking at.
(For whatever it's worth, I grew up with the North American SNES, and I like both designs, but wound up settling into the more colorful Super Famicomey stylings of the AsciiPad controller)