Comment by crote

From a device manufacturer's perspective, it is mainly a safety and reliability issue.

The form factor might be (mostly) standardized, but the cells themselves are not. There's a huge amount of variation between them, and using a cell improperly can quickly lead to some very nasty fires.

This means user-replaceable bare cells go right out the window, and you're left having to build a custom protection circuit for the cells you want to use - which means you essentially end up with custom batteries.

The solution might be a standardized way for the cell to communicate its health and capabilities to the device using it - but good luck getting the industry to adopt it. It provides no immediate benefit to the consumer while making the product more expensive, so they'll only do that when the government forces them to.