This is a great idea, I could see it being used. True, people with a ton of friends would have a problem, but really if you're going to spend so much time adding to your friend list you can spend a second to turn the feature off if you choose not to use it. It would deffinatly help if you were waiting to have some sort of meeting/game that a friend was hosting and you didn't want to stay in the hubs waiting.
It'd be a luxury though, and it may be difficult to properly install, because I doubt there's a quick download for that, it would have to be coded from scratch, and it seems that the best coders on this site are focusing on certain site features in their free time. Even when the coders are done with their task their would be other features that need fixing that all ready exist. It would be a burden on the staff to install this.