Ha! I questioned this in an earlier thread (https://news.ycombinator.com/item?id=24980083)
It's really great to see a response that highlights the reasons (and an acknowledgement that it was something they truly did try to address!).
But, my comment on the promo photo layouts still stand - having the mouse on the left side just for the clean shot must have just stood out for a lot of people. They should just lampshade it - say they're satisfying the lefties for once!