Throwing out some notes for discussion. Wanting to condense a model of understanding that can allow us to see (and execute) that the applied hand techniques are exactly the same as the striking techniques. Same forces, same axis of operation. All these correspond to the sword movements. It's the same thing.
Interested in input and comments as I whittle this down. Cheers...
ikkyo = yokomenuchi (middle) = cutting horizontal Y axis (finished by Z-axis shomen)
nikyo = shomenuchi = cutting vertical Z axis through center
sankyo = yokomenuchi (neck/upper/jodan) = cutting horizontal axis = side-through cut = operates on Y axis
yonkyo = shomenuchi = cutting on Z axis
gote kaeshi = tsuki = thrust = return = stab = operates on X axis (lower gedan tsuki)
shihohage = yokomenuchi (lower gedan)
iriminage = tsuki (mundetsuki) (jodan)
Striking sequence of ikkyo, sankyo, and shihonage are the same. Cutting through Y axis, and then finishing with a shomen cut through Z axis.
Axis reference at http://en.wikipedia.org/wiki/File:Coord_system_CA_0.svg
I think that you're right, they are all the same thing. OTOH, given that initial assumption, you may see why I would also say that spending a lot of time calculating the angles of the various strikes and locks in relation to each other is not, IMO, very useful in the long run.
In other words, the reason why all of these things are the same is also the answer to why dwelling on those strikes and locks overmuch doesn't really help you out, IMO.