According to Apple, the new laptops don't have a battery issue, but that the battery estimate is misleading. For example, people were reporting that macOS would show 3 hours remaining, but then the laptop would actually last 6 hours.
No idea why this came up at the same time as the hardware launch. macOS has had various background sync tasks for a while — iCloud sync, Photos, Time Machine, etc. Sierra adds some background services (specifically, "Optimized Storage") that might have a bigger effect.
No idea why this came up at the same time as the hardware launch. macOS has had various background sync tasks for a while — iCloud sync, Photos, Time Machine, etc. Sierra adds some background services (specifically, "Optimized Storage") that might have a bigger effect.