Because Christ being present to those who need forgiveness isn't the issue as I am sure you well know.

The issue is belief and actions must coincide.  If the Church really believes what Jesus said about divorce and remarriage being adulterous, how can someone who is divorced and remarried without an annulment possibly be eligible o receive Holy Communion when adultery is a Mortal Sin?  Last I checked one should not receive Holy Communion when in the state of Mortal Sin lest they commit a sacrilege. 

I realized that America is hung up on sex--and thinks sexual ethics are all but irrelevant.  The Church does not believe that.  The gift of sexuality was given to us by God--and must be used as God has directed. Sexual ethics, therefore, are not irrelevant but quite relevant to one's spiritual life.