I've seen her several times on Fox News. She also participated in the Republican-backed reading of the Constitution. She's been fairly prominent for a Representative not in a leadership position. Even those Arizonans who vehemently dislike her positions on illegal immigration and health care seem to like her. I like her, and I think that had she not been gunned down, she would have moved on to be a Senator or perhaps even in the White House.
But either way, I think a sitting federal judge murdered and a sitting Congresswoman incapacitated (hopefully not permanently) in a mass murder qualifies to me as a national tragedy. Certainly she and the event have dominated the news cycle. Either way, as titular head of our government, I think it was Obama's duty (if admittedly not a duty spelled out in the Constitution) to attend and speak at the memorial. I'd have thought less of him had he not.