[tzs]

A reasonable manufacturer who is releasing something that updates automatically with no warning to the user nor any indication an update is happening to alert the user that they should not disturb it to avoid bricking looks at the potential cost of a class action suit from people whose devices get accidentally bricked, the potential cost of regulators order the devices recalled as defective, and the potential damage to the reputation. This will almost certainly be more than what they'd save by not providing some way to automatically recover from an interrupted update.

BTW, they don't have to double the flash memory. They just have to provide enough extra memory for a fallback updater that the boot code can load if the main firmware is corrupt. All the fallback updater has to handle is telling the computer it needs firmware and then installing the firmware the computer provides.