Pamela, this is a great point about tone policing and the importance of shedding light on uncomfortable subjects, even angrily and passionately. 

What we're aiming for with Civil Comments, though, is eliminating the personal attacks, harassment, and even death threats that are, unfortunately, very common in online comments sections. None of those things are conducive to furthering actual conversation or revealing "ugly truths." 

Personal attacks, harassment, and death threats only silence people—either through fear or by forcing sites to turn off their comments entirely.

Spirited debate—even angry words!—are acceptable so long as they're respectful of other people. I hope you'll agree that mutual respect is a reasonable expectation for public discussion, even when negative emotions are involved.