For anyone who has ever delved into the world of Medium Format Photography, they will undoubtedly understand some of the benefits of using a square format over a rectangle format when creating photos.
Aesthetic considerations of the image aside, it's just mechanically obvious that a square fits inside of the image-circle produced by the camera's lens a lot better than a rectangle does. In other words, you get more bang for your buck in terms of information/light passing through the lens and onto the sensor/film. Capisci?
Another point to consider is that for some shorter lenses with more distorted properties, the symmetry of the image seems a lot more 'balanced' when going square. If you have ever had a go using a 30mm Fisheye on a Hasselblad V system you will know exactly what I'm talking about. When compared to 35mm / Full-Frame Sensor with a 15mm Fisheye it's far superior in creating a more pleasing image, especially of buildings or architecture. Anything where long parallel lines converge now becomes easier to frame up, appearing less squashed.
As sensor technology becomes cheaper wouldn't it make sense for all the leading camera manufacturers to begin moving towards reclaiming some of that wasted image-circle? (especially as lenses cost so much too). Imagine if you had the option to select what size sensor you wanted to use before you shot the photo?
This topic has been on my mind since about 2007 when I first bought a DSLR, back in the era of the crop sensor and DX Fisheye lenses. Around the same time I had begun to experiment with 120 film. I'm just asking questions a decade later as to why the CMOS & CCD technology didn't move in a larger, squarer direction?
If someone can provide a logical reason to cling to the 35mm format in the digital age I'm more than happy to listen. Thanks