It's a great emotional tool to bring tangible people into the discussion. Although having powerful statistics and logic is nice, it's appealing to see the faces of real people that would be affected by this bill.

I can't find it now, but there was some interesting research done a while back on charities. Turns out that people would donate more to a charity that helps a single child rather than one that helps a million children, simply because the former has a more tangible benefit.