Yet throughout history, even when traitors were drawn and quartered, it has always been customary, as far as I know, to allow the condemned the opportunity to meet with a priest, confess, pray, take communion, etc. Why?

I would call it self-righteous "compassion"...it made them look superior and on "god's side" to all who attended. After all they really did want to "save souls" didn't they, just as this juror has cited?:-<