Well, you will also not be able to get into the boot in a notchback/sedan without foldable rear seats. As far as I know an emergency boot release is mandatory to prevent people getting trapped in the boot, but not necessarily for exiting the car from the passenger seats.
Most cars with electronic door release seem to have redundant emergency releases:
From Tesla to Lexus, more and more vehicles have doors with an electronic button instead of a manual latch. Consumer Reports lets you know how to open them in an emergency.
www.consumerreports.org
To be fair, the MG4 door release seems to be mechanical, but can be dead locked in some cases. Anyway I would expect a physical possibility to open the door when there is a power failure or electronic fault (like in the article linked above).
Or I'll just wait for the MG4 convertible to be released. ;-)