Why does the Xbox wireless elite series 2 controller not have a removable battery?

You have to think that: 15 years ago it seemed something great having a battery removable controller (like the xbox 360 and xbox one), while in these last 6-7 years (for some unknown reason) people just want a not removable battery, with cable. Which is
a great step back because a removable battery is the same with a plus: the fact you can use AA batteries, cable or the battery that xbox would just put in there if it was not removable.

So yes: i agree with you, i prefer too a removable battery controller, but this is what the market is asking right now, and im glad microsoft is finally listening to it

That is very near sighted of you. Even the top of the line rechargable batteries lose their recharging capabilities after a year or two. What then?

it's a big loss to take off the removable battery

I sincerely prefer to be able to remove the battery whenever you want as it is easier to change when you have problems

It's a design decision which I personally also disagree with as a 35 year technical maintenance support person given that all batteries eventually degrade and/or need to be replaced.

Microsoft isn't the only company that does this...many cellphone manufacturer's like Samsung and Apple have also adopted this practice with their newer products. I feel this practice is being done to encourage earlier than normal replacements due to consumers
not being able to easily replace the battery when the time comes for a new battery.