it would be useful, but it can't be.
A. imagine this; Neji runs through the woods, turns up the byakougan, and sees Orochimaru, Itachi, and Madare, so he turns 180* and returns to his village. doesn't sound very exciting, does it?
B.in order for far-view to be useful, Kishi has to know what's coming ahead. I don't think he's completely sure what's the next thing to happen.