Are you implying that the staff kick is not totally and utterly useless? Are you saying that you've actually gained an advantage after you kicked someone??
Actually yeah... kicks are great. You leap forward or to the side and they think you're gonna butterfly, and then kick them right in the head. All the kicks cut right through shields, plus they have a powerful demoralizing effect. Who wants to be kicked on their butt right before they do their killa move? Get's them flustered just enough to maybe give you the edge depending on their personality type. Jumping over someone's special or kata and kicking them from behind is nice. I've also pinned many to the ground afterwards with the staff, which is generally an immediate kill. And of course, there's nothing like kicking someone off of a ledge when they least expect it.
And that's kinda the thing the way it stands... kick is the least expected move at any given moment, and that's it's power. If everybody did it all the time, it wouldn't have the same effect.
But then of course, there's the even more rarely seen Hilt Bash...