The thing about phones and laptops is that they have the excuse that miniaturization makes this necessary (it's still an excuse but it's better cover). And current systems essentially have the lifetime of the battery.
Cars should be a different story but we'll have to fight for that even.
And ingress protection, which requires excellent seals, which need a bit of know-how (i.e., a shop) to correctly reapply. At least that's what I like to tell myself.
Battery packs are structural components for safety reasons more than anything. Weight and volume savings are secondary to safety in regards to anything with high energy density, be it a battery pack, fuel cell, or gas tank.
But though they _contain_ batteries, a battery pack is not a battery any more than a car is an engine. The battery inside the battery pack remains non-structural and non-load-bearing.
>with the battery cells helping to solidify the platform as one big unit
The individual cylinders are made from steel. The steel is used structurally. Perhaps next you'll tell me the "battery" is actually just the anode, cathode and electrolyte?
It depends on 1 ("one") legislation. Its not like theres inherently anything stopping this from happening except the insatiable hunger of some rich dudes. I believe the EU is forcing the iphones to have usb-c?
I've swapped batteries in iphone and macbooks several times. Just because the manufacturer doesn't really want you to do it doesn't mean you can't do it.
Cars should be a different story but we'll have to fight for that even.