I always thought removable batteries were clearly a good thing, until I watched this YouTube video: Techquickie - Why Removable Batteries Are NEVER Coming Back

While acknowleding the pro side, it also gives some arguments for the con side:

• phone cases are easier to make water proof if they are not meant to be opened
• sturdier battery case for safe and easy handling makes the phone heavier and bulkier
• customers favor metal/glass phone cases, but those tend to break when frequently opened
• non-rectangular batteries allow for more compact hardware design

The video is 4 years old and I haven’t followed the topic too hard. I just found it interesting to have some fairly reasonable counter points for a nuanced discussion.