No, not missing your point. There was a pre 9-11 mindset that allowed it to happen and a new mindset after that horrible day. Bush reacted to protect American Citizens after that day and was successful in not allowing such an event to happen again. To lay the blame for that day on Bush's shoulders is leftist folly, as much of the reason is the years of neglect we had in our intelligence efforts.
Would I blame Obama if it happened during his tenure? Well, depends on what and how it happened. If it happens due to policy changes he has made, yes.
"Always look on the bright side of life!"
Eric Idle