If I don't have business being in the sanctuary, I don't go in there, regardless of if there is a rail or not, so a barrier already exists, be it visible or invisible. Most lay people don't have a reason to go into the sanctuary anyways...the main purpose of the Communion rail is for you to recieve Our Lord kneeling. If we can't have a Communion rail because it's supposedly a barrier, why are Eastern Catholics allowed their iconostasis?  Even Episcopalians, Lutherans and Methodists have rails, it's only low-church liberal Catholic types that want to force us all to stand.  Are kneelers in the pews useless too?