You raise a good point here stateofgrace and I'm not reluctant to admit it.
I'm not going to look up my post for my exact wording but the essence of what I said was they planned for WTC7 to be within the collapsing WTC 1 debris fall.
I believe that WTC7 was indeed a controlled demolition but I can only speculate about why they did it and as you alude to, why didn't they do it differently.
The best answer I've heard proposed, is that it was a major screwup.
The scenario has it that the collapse of WTC7 was planned to occur under the debris cloud from the falling WTC1 and be blamed on the WTC1 collapse.
http://img220.imageshack.us/img220/5905/gjswtc34rto9.jpg
Hidden by that massive debris cloud, a CD of WTC7 would be well masked while guaranteeing the total destruction of WTC7 and it's contents..unlike a topple which would produce far less predictable results.
Something went wrong and they failed to trigger the demolition in time with the WTC1 collapse.
That obviously presented two problems.
They had to finish the job (CD WTC7) and they had to have some kind of explanation to account for it's collapse.
Once they corrected the problem with the CD, they allowed time for the debris damage and fires to build a case for the re-planned collapse.
MM