About this investor's meeting, can we really expect anything more than a few choice quotes?
11.5 hours and we will find out.
concerns over Nintendo fixing problems that don't concern him
You have to remember that Nintendo is a Family Oriented company, so they are thinking of the entire family.
You say people can just go play their consoles on another TV, but who really wants to go digging behind their TV to unhook the console and move it to another TV everytime the GF/Wife needs to watch her shows or you need to watch the game? In that moment you can just stream to the controller instead and carry on with what you were doing.
In other occasions the devs could use the controller screen like it was a DS HD or use the touch screen for puzzle elements or Mario Paint HD. At the same time, I'm sure it would be programmed to be compatible with NoTV Stream Mode as well.
Other instances will be able to use the screen controller for a personal screen to avoid screen cheating, like split screen local multi during a FPS hide and seek death match or picking plays on Madden 2013 or creating audibles on the fly.
There are tons of uses for a screen in the controller and being able to switch the game from the TV down to that screen in your controller. I for one might like to continue my game while I it in the kitchen with my girl and help her cook without having to run back and forth to and from the bedroom or maybe take it outside/in the garage and keep playing while watching the kids/dog/etc/whatever.
As far as distance, I'm not sure, but I would assume it would work like Wifi and have stronger signals the closer you are, so I wouldn't wander too far off. Frequencies likely shouldn't see any interference from the usual sources (cell phone, cordless, wifi, microwave, etc.). If you really need to travel and think you may be out of range, you still have the 3DS as an option though.