There's nothing wrong with internal lithium ion batteries. What should change is the ease of access to them. According to ifixit it's around a 20 minute process to unclip the bottom of the DualSense controller, replace the battery and reassemble. The cost of the battery is about $20ish dollars as well. Given that the batteries last for several years, and you can even buy higher capacity ones, I think that's a great solution. The only way this could be improved in my opinion is if manufacturers had a screwed-shut flap on the back that enabled easy access to just that compartment.
But let's play devil's advocate here. Let's say in this scenario controllers still use AA batteries. I invest the $35 into a four pack of eneloop AA's and a wall charger. Now I have to keep track of the batteries, have make a permanent spot on my wall for this damn charger to live that I use all the time, and then, in a few years, buy more fuckin batteries because EVEN THESE WEAR OUT! I'm just... making the original problem more complicated! All this versus just plugging in the controller into the same damn cord that I use for my phone and my steam deck and my "massage gun" and my laptop and all the other shit around that uses this charging interface.
TL;DR: $20 and 20 minutes of your time every couple years is not that big of a fuckin deal.