The reason why your Xbox controller still uses AA batteries
Every console cycle the same debate resurfaces, and Microsoft keeps landing on the same answer. AAs give you instant power when the controller dies mid-session, they don't lose capacity after a couple of years, and you can swap in whatever brand you trust. That last point matters more than the specs suggest: a controller with a sealed battery has an expiration date, while an AA-powered one can outlive the console itself.
I think the real reason is simpler than engineering elegance, though. AAs keep the controller cheap to make and cheap to ship, and they push the cost of power onto the player. That's a quiet financial choice, and it's the same logic that keeps the base model at a lower price while Sony eats the cost of a built-in pack.
What I'd want to know is whether this still holds as controllers get more expensive and feature-packed. If the next Xbox controller costs more and still takes AAs, the argument gets harder to sell.