It's hard to reconcile the popular folk hero that is Einstein with a letter like this. I suspect a lot of this may come from us not being in a position to judge people from almost 100 years by the standards of today.
I suspect that even a century ago that list of demands would have been seen as very cold and mean.
Requests for lack of intimacy are understandable, given the no love situation. It is strange that the household chores are described - at the time it would be 100% understood that it would be so even if it wasn't written down; apparently it was a problem in their past. I mean, at that time and place, wife not cooking for you would be reasonable grounds for divorce. The "no belittling before our children" is natural as well.