The old Kirby 1 “extensions” had package.json files. Back then to be machine-readable for kpm, my Kirby package manager that never got finished (also because all plugins are different and can’t really be installed automatically).
But I agree that some standard to define meta data would be great. However I don’t think that the Panel will be able to display the information because of the, well, different ways plugins are currently installed. Also see this and this topic.