What would you use that information for? Would you refuse to use an online service, smart device or video game based on how much storage space the app asks for? Even though the actual space they will end up using might be only half of that or even less?
For an app you haven't used in awhile, you'd probably uninstall it.
For an app you're actively using, you'd probably accept the update, but there would likely be pressure on the devs from the percent of people who would uninstall it instead. I think the hope is that this would cause them to think twice about bloating for no reason.
