I think for a lot of people it would ruin their optimistic world view. If you can believe that everyone can recover from anything no matter how traumatic, life isn't as scary. When people can actually face permanent damage and/or wind up dead in the long run thanks to the scars from abuse it makes reality that much more frightening. When you realize that you start to ponder if you or perhaps your child could wind up permanently damaged and left having to "cope" with life by someone else, or just how much it would take to push you to suicide. I think most people who aren't already suicidal like to think they could never be driven to committing suicide but I'd say they're wrong. Everyone has different degrees of pain tolerance, but everyone can be broken in the end.
And then I do think what alizee said is true as well. A lot of people just don't know what they could do to prevent or stop it, so to them it's an "oh well" sort of thing and they just don't want to really have to acknowledge how terrible reality is. The legal system is corrupted/broken/underfunded when it comes to protecting children, as well as things like lack of evidence, and pervasive beliefs that a child is absolutely almost always better off with their parents. I mean some kids are taken from their homes due to extremely dangerous circumstances and all it takes to get them back is taking a few anger management classes or passing a few month long rehab program.
From my experience most people will sit around saying "deal with it" or some variation of that to anyone who has experienced any sort of tragedy or trauma (unless it's been popularized by media and they can hop onto some sort of bandwagon), right up until they go through something horrific at which point they begin to moan and complain about how society doesn't care, there's no help out there, how could people do such a thing, how could people be so evil, I am left with lasting scars and have to cope with life now, etc.