Flashlights are certainly a hobby for some of us, but they’re also a common tool most people have an occasional use for. Standardized, field-replaceable Li-ion batteries are common in flashlights targeted at a non-enthusiast market.

On-cell protection circuits are quite bad, protection should be inside the device.

I agree that devices should not over-discharge or over-charge cells, but the example you gave was people putting batteries in their pockets, presumably with metallic items like coins and keys that can cause short circuits. On-cell protection circuits handle that situation well enough; I recommend carrying batteries in plastic cases, but I’ve never heard of a manufacturer getting sued over a protected cell.

I often use unprotected cells myself, but I’m a hobbyist.

[New EU rules don’t] mean the batteries should be swappable. It will only make service workers’ life easier, not yours.

The new rules say that batteries should be removable and replaceable by the end-user. They don’t seem to encourage standardization of battery types though, so they could still be proprietary and ridiculously priced.