and what was the point not to buy from Sony Semiconductor ?
I would like to know the answer too. My best guess is that it is because (1) there is some custom work needed (microlenses adapted to handle wide angle lenses) and (2) Sony is not interested in custom work in what for it are very small quantitities, while the far smaller company CMOSIS is more oriented to doing small batch custom work. For one thing, the CMOSIS web-site advertises "custom(ized)” products.
Q2. Why not Teledyne-Dalsa, which also does custom CMOS?
My guess: its custom CMOS is oriented to industrial, scientific uses like X-rays, and is not well suited to high quality "standard" photography.
Q3. Why not a CMOS sensor for the new S also?
My guess: a CMOS S might come, but its higher costs, lower volume, and far smaller loyal customer base mean that the Leica M is the better place to start. Also, CMOSIS already offers 36x24mm in standard products, but nothing larger, so fab. ability might be a limitation.