^ I agree, but often times unless you are very close to the stage you end up watching the screens a good amount of the time anyways unfortunately. But I don't know if your explanation actually explains why she does it. She certainly didn't always do it and people have known about stage visibility for a long time.
I just think she has gotten more and more over dramatic over the years and somehow got it into her head that it actually looks good (same thing holds true for many of her recent photo shoots and music videos actually, aka mainly the kazuyoshi ones^_^). She's done it in a number of TV lives now too and obviously that is for people to watch on their tv screens, not to be seen on a stage from an audience member far away.