I think you've highlighted the various ways people fall into the state of denial.

"Wasn't that bad" (the get over it comments)

"That was a long time ago" (ancient history)

"They're worse than we are" (people who are worse don't get sympathy)

Honestly, I think its a good sign these type of incidents are now publicized. Maybe large segments of Americans still don't "get" racism, but maybe a few of them, each time something like this happens, will be bugged enough to try to learn what's really going on.