I think what is happening is that Canon is going after the high-end segment of the commercial medium format camera market.
They are trying to compete with the medium format professional cameras such as those from Hasselblad. Those are $45,000 cameras with sensor sizes of 32.9 x 43.8mm that capture just incredible detail and produce 65 MB files per image. Hasselblads are used for high end fashion and commercial product and advertising photography where the images are blown up to poster or bill-board size.