Philippe, I began my photography journey with a Rolleiflex. The first photo class I took at university, I printed to fill the 11x14 or 8x10 pieces of paper. By my second photo class I realized my "error" and started to print what I saw instead (square), and stopped worrying about the "extra" photo paper. There is a visual movement within the image that is unique to the square format....a circular movement that, to me, is more natural than the hort. and/ and vert. movement usually occurring within a rectangle. But then I like making 4x10 images with my 8x10 camera, also! LOL!
Vaughn