I think the problem is that it's deadly. Tracks these days don't seem to have the problems that older ones did. I remember seeing people pancake into the overpasses or fly off the track completely. Don't see much of that these days -- must be safer tracks.
Of course, you smack into something going head-first and it's curtains.
I used to do this on my skateboard when I was a kid. "Superman Style" is how I refered to it at the time cuz you put yer arms out like you're superman.