If we look at pictures of WC and JKD stances, couldn't the same be said for them?
-> In the 1st picture, the face and groin are open. (...and gut?)
-> In the 2nd picture, the face and liver are open.
-> In the 3rd picture, the face and chest are open.
I am at fault for saying the centerline isn't exposed in post #8, though. I meant to say that it isn't unprotected, which is a bit different
I apologize for any misunderstanding.
My central point is that i doubt you could come in and land a centerline strike w/o getting hit in the face... I imagine this is where trapping would come in, or a deflection at least.
On an related subject, in the video you have on Members In Motion your face is wide open. The face is an important part of the centerline
(elbows in, not just horizontally. keep them closer to your body. you can move your arms forward a bit if you have to.)