It's not that I disagree with you entirely. It's just personally, knowing how to solder, and having had to replace batteries for both external and internal battery laptops recently, I'd rather not have this extend to laptops. As it is now with modern laptops, you just open up the housing, desolder the old battery, get just about any lithium battery from anything (those cheap USB power packs are great), and solder some wires from that to the control board. Going back to detachable batteries means having to deal with every single manufacturer's proprietary awful housing and pinout slots. You either buy an OEM part from the manufacturer (if they still sell them) or risk a fire with third party batteries in awful housing. Detachable batteries is also how you end up with things like Lenovo using firmware to disallow third party batteries from charging on their laptops.

I feel it's more important that housings should be user openable with normal tools (guitar pick, razor blade, screwdriver) without damaging the housing. HP is genuinely awful for this on laptops.