I can't see how you could copyright a packet layout? Even a seperately devised system has to contain the same data, so would end up much the same. Plus it's easier for the guys at the hardware end to only have to deal with one system.
I just thought that it was interesting that a packet structure from a small indie game could become the standard used by Codemasters I'm sure there must be other layouts in use by bigger games, yet they chose OutSim for some reason.
You say that, but motion simulators for the home market is a very recent development. I'd imagine all prior motion simulators were tied to a single piece of software they were made for, and just used a proprietry communication method.