Your battery life is great now, but what about 3 years from now? The current ~2 year phone refresh cycle should not last forever, and I think that both the S7 and the nexus have it wrong when it comes to batteries. Even at a gentle 50% Depth of Discharge, a typical li-ion is at only 70% capacity after ~1200 cycles. Bump that to near 100% DoD, and you're at 70% after only 300-500 cycles. Sealed-in batteries in a phone are, IMHO, even a bigger deal than the lack of expandable storage.

Reference:

http://batteryuniversity.com/learn/article/how_to_prolong_li...