Yes, it's true that Huey Lewis and the News sang a song by that title back in 1989. But I am referencing that phrase with regards to decorating.
Wall art such as photographs and painting are quite often in rectangular shapes. One reason for this, especially with photographs, is the common frame sizes. Unless you want to pay for custom framing you are pushed into the sizes that are easy to frame. Fortunately we now have some options that don't require framing. Photographs can be printed on galley wrapped canvas, metal and acrylic. None of these require a frame and all are quite beautiful.
So choose a square photo if that is what best fits your space and budget. It's a nice shape and a great option if you want more than just a rectangle.