>> In my experience 10" is too small for a laptop. 13.3-14" is perfect and still quite portable.

These things are so variable from user to user-- speaking for myself only, 13.3-14" is too small for me to use as a daily driver.

On the other hand, I also have an original Surface Pro, and the small screen is usable for me when not being used as a daily driver.

If Microsoft didn't think there was a market for the Surface Go, I highly doubt that they would have made them.