We are excited to announce that we have launched our new Hive Community! HiveNation will remain as an archive, but all new posts, discussions, and articles will be created on Hive Community. You can visit our new community at thehivecommunity.aerohive.com
Bandwidth usage over time as an overview is not currently visible in HMNG. You can view connections over time for the network, bandwidth over time for an application and bandwidth over time for a user/device - the only thing missing is an overview of bandwidth over time for the entire network.
As Luke suggests, using the feedback button is your next best option. I have personally seen the feedback > implementation statistics and feedback is certainly taken seriously :)