The fact that I'm personally extremely unlikely to be killed by either terrorists or cops isn't the reason the statistic is important.
The statistic is important for public policy debate because there is 8 times more progress to be made in terms of saving lives by dealing with the problem of police killings.
It's interesting, but it isn't the only needed info. You might have 8 times as much opportunity for progress, but it might be 8 times harder to make progress.