After giving this some thought, I think they also tried to remedy one of the problems with J-cords: uneven pull-force distribution.
The normal J-cords are basically one long cable that goes into your left ear with an extension to go behind your neck to your right ear. With this construction, the whole weight of the cable and every pull exacts it's force only on the left side. The right side is strain-relieved (to some extent) by the neck. That's a normal J-split without that big mic/button complex mind you. With that thing added you'll probably have to get used to often pulling the left piece out of your ear (had this problem with my previous J-cord cables).
Now, if you change the split to the way it is on the MH1C, the long part of the cable goes behind your neck to the right ear and thus the strain on the cable is relieved by the neck. You're left with a relative small extension cable to your left ear and on that the added mic/button-thingy doesn't matter that much.
But this is just a theory of mine (unless Sead can comment on this?)
Btw: for me, if I balance the lenghts of the cables on the left and the right side, the split rests directly on my neck and doesn't hang in the air. Might also be by design to cancel out the pull-force...