It’s all depends on device size and required capacity. AA is not a bad choice for many cases. And there are other replaceable batteries with higher capacity e.g. 18650.
Most modern devices have an integrated 3.7v Lithium battery so standardisation should be possible but I see no market forces for this - devices with short lifespan (limited by a non-replaceable battery) are more profitable.
That's true for smartphones (I had bad experience with Android from 2 big vendors which stopped updates around end of sales date) but many other battery powered devices don't need regular security patches.
For me, this limitation applies only to my phone. I have plenty of other wireless devices and deliberately prefer devices that can use AA batteries. One reason is that I don't have to manage the multitudes of internal batteries as much and I need only 1 battery charger with batteries always ready to go. And obviously, battery going bad won't make my device useless (My DS4 controller's internal battery went bad in about a year. So I'm sticking with xbox controllers.)
Most modern devices have an integrated 3.7v Lithium battery so standardisation should be possible but I see no market forces for this - devices with short lifespan (limited by a non-replaceable battery) are more profitable.