Probably because NBC, like the other networks, is trying to finalize the fall schedule and they don't want to prematurely say something is canceled or renewed before having all their ducks in a row.
Remember last year when CBS announced that Unforgettable was canceled, and then a few weeks later they were like, "Oops, we meant to say this was renewed!"
They announced the renewal of some sure bets to generate buzz and gauge reaction. In two weeks we'll know the fate of basically every show. I'm sure Community fans, Body of Proof viewers and many other shows on the bubble are just as nervous as some of the Smash fans on this thread.
Marie: Don't be in such a hurry about that pretty little chippy in Frisco.
Tony: Eh, she's a no chip!