If you make a battery removable you've got to completely redesign the device.
You've then got to put a plastic case around the battery,
and then you've got to create a plastic socket inside the device,
and then you've got to create a removable case that will come off.
You've added actually quite a lot of extra just volume to the product,
and then you've got to redesign where everything is inside to make room for all of this.