The better cell cameras get, the more extinct point and shoot cameras get. And the more extinct point and shoot cameras get, the more important cell phone image quality gets. OIS is not a miracle technology but it helps with a variety of situations:
low light
shaking hands (my wife had to stop taking pictures because of this)
close subject (same effect as telephoto)
action photography (camera moving too)
action photography (panning)
document scanning / check deposits (I've stopped visiting the ATM)
It makes bad shots good and good shots better. And reduces the work needed for both.