I would be slightly less irked now if Apple do reduce the battery capacity in the 6s, not because I now care any less about battery life but more because I can think of one possible reason why Apple might do this. This is cut-and-pasted from a post I made on another thread...
... I think that if the rumours are true of Apple reducing the battery capacity in the 6s (from old 6 1810mAh to 1715mAh in the 6s -
https://www.macrumors.com/2015/08/03/iphone-6s-6c-1715mah-battery/) the reason might well be because of the iPhone 7. Apple might have some serious battery challenges coming up in the 7 so it doesn't want to set the bar too high with the 6s in terms of being able to maintaining 6s battery life with the 7, or maybe being able to implement a plan of adding only an hour extra at each iteration.
The main thing that I can think of that might cause issues in the 7 might be dramatic reductions in size of bezels, maybe to the extent of removing the home button and bottom bezel entirely, which would mean a smaller overall physical size and hence less volume to accommodate the battery if Apple keeps its obsessive focus on making the device as thin as possible still.
If my theory above is anywhere close to the truth then I understand Apple's reasoning and it is actually a good thing for me because it would give me a smooth increase in battery life as I upgrade through iPhone 6s and then on to 7 if that is what I want to do. Instead of having battery life figures (let's just pick one, video playback) that might go something like...
iPhone 6 - 11 hours (official published figure)
iPhone 6s - 14 hours (Apple put in the biggest battery they can fit)
iPhone 7 - 12 hours (because the available space for the battery just got a lot smaller)
I would get...
iPhone 6 - 11 hours (official published figure)
iPhone 6s - 12 hours (Apple put in a smaller battery than the maximum that space would allow)
iPhone 7 - 12 hours (because the available space for the battery just got a lot smaller)
Maybe Apple can squeeze enough extra efficiency out of 7 hardware that the progression might actually be 11/12/13 even with a much smaller battery in the 7 which would be nice, but in any event I can now see at least one possible explanation for Apple deliberately reducing battery capacity in the 6s not out of wilful disregard for user's cries for more battery but to give an overall better experience across generations of device.
I'm still hoping that at some point everything will get thrown at battery life, maybe including radical new battery design and/or chemistry, and the whole industry will shift from targeting getting through a day with moderate to heavy use to being able to get through a weekend or even a week with moderate to heavy use because that would allow me to go away for long weekends or shortish business trips with no concerns about needing (or forgetting to) pack a charger but we are where we are with current technology so it's really a matter of juggling what is possible for the best user experience for the maximum number of people.
