The morality and ethics of dying with dignity are perfectly simple, rational, and humane…
Nobody else has the right to dictate what I can or cannot do to my own body. I have the inalienable right and freedom to choose as I please—as long as it does not infringe upon the freedom, health, or safety of anyone else.
Likewise, nobody has the right to dictate what another knowledgeable, skilled, and compassionate human being can do to help me peacefully and painlessly enter the eternal sleep—at a time, place, and manner of my choosing—and with the same care and love that any decent person would bestow upon a beloved, suffering animal.