I'm wondering why a company has not made a fixed gear hub that uses a shimano spline pattern that is just stationary and fixed to the hub? it seems to me that if you did that you could use regular old shimano cassette cogs which are cheaper then the track cogs (9 for $20 in assorted sizes!), and would be easier to take off (no chain whip needed). It seems to me like that would be the way to go. you wold never have to worry about locktighting your lockrings or anything.
Has this already been done before? is there something I am missing?