I think it is pretty strong to suggest that 9/11 was the worst attack on US soil ever without further justification. During the Battle of Gettysburg, for example, more than 7,000 soldiers died after Lee's army attacked the US army. The Attack on Pearl Harbor might also be in contention, depending on how severely you rate the crippling of the US Pacific Fleet.
An attack 80+ years ago does not underscore the need for any reform today, nor for that matter does an attack 20+ years ago. Not unless you think nothing has changed between then and now, which would be silly. Introspection and reform after both those attacks happened years ago. It may be the case that we do need additional reform today, but that isn't evidenced by attacks which occurred generation[s] ago.
I think it is pretty strong to suggest that 9/11 was the worst attack on US soil ever without further justification. During the Battle of Gettysburg, for example, more than 7,000 soldiers died after Lee's army attacked the US army. The Attack on Pearl Harbor might also be in contention, depending on how severely you rate the crippling of the US Pacific Fleet.