I disconnected my Kinect quite some time ago not because of voice commands but because of hand gestures. My wife and I would be watching something on Netflix, and we'd be talking about whatever and gesturing with our hands and all of a sudden it would stop the movie and go back to the main menu, or switch to something in our favorites. Annoying as hell. Having Kinect be always required, not able to be disconnected, is a big incentive for me to NOT get this console (though I suppose you could always put some sort of cover over it, but you shouldn't have to).
Account management and game transfer shouldn't be a problem if you console bricks itself, unless they took a huge step back in how their accounts work. XBL accounts are already set up so that you can go to any Xbox you want, sign in to your account, and download whatever content you own. There's nothing to suggest it won't work that way still (and the fact that they say you can take your disc over to a friend's and sign in to play it suggests that it will work that way).
Now for my response to the presentation from someone who has always favored Xbox over Playstation:
I don't give a shit about all this sports, live TV stuff. I don't even have cable TV (though I do have cable internet).
I hate Kinect already for voice and gesture commands, why in God's name would I want it to be integral to the system and unable to be turned off?
Where are the games?
@FMW: I was incredibly disappointed by this presentation. I know this is the direction they've been headed in a while, but I'd hoped they would get themselves turned around. I definitely won't be getting either console for quite some time after release, but the PS4 is looking a lot more attractive for when I eventually do. There's not a single thing they showed that I care about that PS4 can't also do.