What gets me is all these people complaining about the battery, yet no comment about actual battery life. My wife got the S8 and I have the Z2. These phones go toe to toe on actual battery life. Also, another thing that bugs me, is everyone saying "This phone should be able to stand on its own without any mods at all." Really? You're going to get a Moto Mods phone and not get any mods? Then why get one? Get the S8, or upcoming X.
I think Moto decided that you will run a mod, and a mod usually has 1,000 mAh built in, at the very least. Thereby giving you 3720 mAh battery. And that little bit of thickness makes a difference. After using my Z2 Force for a bit, I picked up the Z2 Play at the store and it felt super thick. Most of the time, now, I just run a style shell because the built in battery is enough. Though I did pick up a battery mod at Best Buy that was on clearance, I don't really have any need for it unless I'm going to Disneyland or something where I might see heavy usage (stupid lines) without any chance of charging the whole day.
I will say about style mods though, I wish they had metal plates or something built in so I can use my magnetic car mount. As it is, I have to carve out a spot to put the metal plate. Looks fine when its on the phone, but it was a pain to do.