Too many top apps were dependent on constantly waking up and doing network or other expensive jobs. So for M Google says 'these things won't happen when the user leaves the phone on a desk for 30m+' which spurs people to prepare for this new world even if they won't encounter it much. Now with N Google is saying 'this will happen when the screen is off for a few minutes' and now any decent app needs to prepare for this, but the best apps already got into this new world for M.

That's really the thing doze is great at. If you forget to charge your phone, you wake up with still decent amount of battery left. Or for tablets sitting around on tables/desks.

I do however, sit/stand at my desk for 8-9 hours a day and maybe pull the phone out less than once an hour. I would like the phone to be in Doze mode when it's in my pocket, rather than forcing me to have to put it on my desk. As I said, I don't like leaving it unattended, even if it's simply to step away for a few minutes to the watercooler.

Doze backs off sync period, trading timeliness for battery life. That's why significant motion prevents it from happening, it assumes that if it's on your person then syncing is important. Which is a generally true assumption.