Ummm, why is this a big deal? Am I missing something?
This looks like just a way to limit content for little kids so that they get appropriate content when they fire up the steam machine. It doesn't mean your friends can play on your account at the same time.
This seems to be accurate. I don't know what the big deal is. Sure, it's useful, especially if you have a steam machine that small children play on, but it doesn't seem particularly amazing.
This is pretty crazy in my opinion. I just love this feature and I personally think it's very good for steam's customers. I waited a while for this :D now all i need is a steam controller.