mobile

That's the only reason I can find... Some manufacturers justified that they sealed the battery so that they can have slimmer body but it's not really the case on the zenfone 2 (sidenote... I don't understand why the power is on top and vol keys on the side if the purpose was not to make the bezel slimmer... LG said they put the buttons at the back on the G2 and G2 to have slimmer bezels and they do have slimmer bezels but zenfone 2 bezels are not thin at all). You can see they could easily have made the battery removable... there's room in this big body.