To the uninformed layperson, they look like they could be a pair of lights, but because they're sort of futuristic/robotic-looking, brightly colored, and nestled behind the grill just far enough back to be out of the way, but just far enough forward to be noticed, people see them and wonder just what the heck they are.
They definitely work pretty well too. I've used them to wake people up when they're stopped for longer than they should be at fresh green lights or, like you said, to avoid disaster when other vehicles begin to drift into my lane.
Style + safety + attention = why I like them. I also like that they're generally accepted by the Subaru community too - and now that I think about it, I don't know if I've ever seen them on any other car.