Even though 9-11 was shocking, it wasn't as big of a deal in the grand scheme. After the invasion of Afghanistan, most of the world moved on from the incident. I know it's hard to see it that way for Americans who were being lambasted by the media for years after, but most people in the world didn't hold onto it for that long. Really, 9-11 was just a pre-text for a new phase in American foreign policy.
Pearl Harbour had much longer lasting repercussions that affected the foreign policies, and eventually domestic infrastructures, of dozens of nations. It also lead to the direct confrontation between the U.S. and the Soviet Union.