I think not, because batteries need to have their voltage controlled along their lifetime so they don't degrade and maybe burst, and that must be done at a low

I think not, because batteries need to have their voltage controlled along their lifetime so they don't degrade and maybe burst, and that must be done at a low level. It's a compromise between safety, performance and durability. Replaceable batteries might be more difficult to use and have their performance reduced for safety. Although it doesn't warrant planned obsolescence, of course, but those security/performance things might be another excuse to reduce consumer choices.