Greater energy density is possible with OEM batteries. My G9 has a 7.2V battery, even though that battery is roughly the size of 2 AA batteries side-by-side. To get something close to 7.2V with AA batteries, one would need roughly 5 AA batteries, requirping a much bigger battery compartment. All that adds up to bulk.
All that said, most modern cameras can charge through the USB connection, so if you do happen to forget your charger, you should be able to use an alternalte charger, like a phone charger, in a pinch. If you pack a few spare batteries, then, on average, you'd be going several hundred shots before running out of power.