Over time all things move to the center... including opinions and moral choices. I'll use "killing" for my example. The Bible specifically states that "killing" is a sin. Period. Then there are those among us who believe they should have the "right" to decide the fate of another life. This is not a discussion of capital punishment or war, but of all other instances. Now the Vatican, bowing to the pressures of mankind, has determined that the Bible's edict needs adjustment.
When we as a society decide to alter what is black and white to fit within what we think will be pleasing to others we are compromising our society's ability to sustain itself. The long term effect of this particular choice? At some point it will be "reasonable" for someone else to determine if your "life" is worth living.