Lots of advantages, but one major downside: you can't pop the empty battery, put a new one and keep working.
There's a reason professional devices (e.g. cameras) still have replaceable batteries.
There's a reason professional devices (e.g. cameras) still have replaceable batteries.
Reading the comments here, it's obvious that the replaceable battery fans can't even agree on what they want. One commenter wants the back covered in tens of screws for waterproofing. Other commenters want the battery quickly replaceable so they can do hot swaps without missing a beat. Some people are sharing links to phones that have replaceable batteries and getting responses from people saying they'd never buy that phone because it's too big, too ugly, or other reasons.
This is an impossible debate because one side has convinced themselves that it's possible to have their cake and eat it, too: They believe that removable batteries can be implemented without any tradeoffs and the only reason they're not removable is so the phones are forced to become e-waste, which requires you to ignore all of the low cost battery replacement services available.
There's challenges adopting standardized rechargeable batteries, e.g. trying to recharge alkaline batteries risks fire/explosion (and you know that will happen far too often given the number of people out there), but if we have had standard battery sizes, voltages, and capacities for rechargeable batteries, things would be so much better.