Yet this is the posture which makes sense given what the activity is.  Facing with the people at their head to offer the sacrifice.

He also did not command many other things.  Sunday obligation, screens in confessionals, not going around buck naked or walking on our hands.  We are not Muslims reading commands from a manual.   Guided by the Holy Spirit we made use of our God-given capacity to reason.  The rite developed organically to the the way it is/was because the semiotics are correct.

And versus populum was a failed experiment.  The semiotics were wrong from the start, much confusion (and loss of faith) resulted, but our predecessors didn't realize this until it was tried.  Now we know better; how long shall we persist in a mistake?  It doesn't help that this practice was imposed on the people primarily by lying about the Vatican II texts.  Shows that it may not have been an innocent mistake.

 A return to Vatican II sources, as Pope Francis is calling for, is overdue.