"I know being nicer in tone lets me get away with violating some taboos,"

Niceness is essential. It is part of leaving a way for the other person (or you) to change your mind. It is even more important when discussing life-and-death issues.

You have to be able to say "I think your proposal would cause millions of needless deaths, and my perception of your attitude about this makes me think you're a monster."...WITHOUT the discussion exploding.

Because generally you're not talking to idiots or monsters, and working out a better common understanding is the only thing that will bring all parties closer to the truth.