Gah. You do all realize every time we change the title we kill thousands of links in?
A better google comparison would be "september 11" "attack" -terrorist vs. "september 11" "attack" "terrorist".
Shorter phrases will pretty much always have more hits than longer equivalent ones.
The change from "September 11, 2001 Terrorist Attack" to "September 11, 2001 Terrorist Attacks" was in my opinion completely unnecessary. But I understand people's need to make an imprint.