Well, the fact it was one of the most important buildings in the US, you'd expect every effort to save its contents, if not its structure. Is the amount of data saved or recovered of no interest to anybody, regardless of it's relevance on the events of the day?
I think you are asking far too much of the FDNY if you think that they should go into a burning and structurally damaged building with no water supply to fight the fires, even locally for self-preservation, simply to recover data. How many lives do you think the data in WTC7 was worth? One? Ten? A hundred? Because that would be the tradeoff. There was nobody inside, and no way to fight the fires. How many file servers or filing cabinets worth of data were there in this 47-storey building? How would the FDNY know what needed saving and what didn't?
Really, asking firemen to go into a building this large, without water, to blunder about at random trying to rescue bits of paper and disc drives, when what they find is more likely to be irrelevant rubbish, is quite, quite insane.
"Mom, tell me how Daddy died again."
"He was a real hero, son. He tried to save the SEC paperwork when everybody else had given up. They found his body in the wreckage, clutching a report on the excessive use of paperclips."
"(sniff) I'll never use a paperclip again unless I have to."
"Good boy. That's how Daddy would have wanted it."
And, of course, any relevant data that had been rescued would now be cited as evidence of foreknowledge; how did the FDNY know exactly where to look for the files that the conspirators wanted to recover?
Risking firemen's lives to save data files from a burning building. Pathetic.
Dave