i loved the first movie, but i had a quick question-why did they shut down Sector 7? i mean, if it wasnt for them, we'd be in trouble. someone else would have gotten him out of the ice, whether it was other countries exploring the northpole or Decepticons, and all the devastation here on earth would have been greater. they should have been kept open to have a sector of the govt specifically to deal with these robots (though that could be the new NEST group, if they still exist) only reason i can think of would be because its outdated, and they have nothing left to guard, but again-Communications with the autobots and designing new Decepticon-fighting weapons would be the smarter choice (again, unless that is the purpose of NEST your thoughts?
Sector 7 weren't exactly be best intentioned of people. Nor were they effective at keeping their operations and the existence of the TFs a secret. They were closed because they failed. NEST is an alliance between us and the Autobots and is very much miliary rather than secret service orientated. Sector 7's purpose was to hide Megatron and the Allspark while gleaning as much technology from them as they could and simultaneously keep these things secret from the world. (As I said, it failed.) NEST's remit is to work with the Autobots to eliminate any Decepticon threats and is, apparently, a global rather than exclusively U.S. operation.
S7 was disbanded because it had grown to be too much of an independent entity. The higher-ups, like the Secretary of Defense and the President didn't even know about it, much less have a say in it's operation. Don't think of it as them "destroying" S7, think of NEST as basically a reintegrated, reorganized version of it. A 'franchise reboot' if you will.
Since the government's forged an alliance with the Autobots, I don't think it'd be a good idea to continue an organization that was willing to experiment on their own kind and who's nature was a bit antagonistic in its efforts to acquire intelligence and/or prevent public exposure of certain information/entities. If I'm an Autobot, I wouldn't be too thrilled about allying myself with an organization that had been assigned and trained to hunt me down (even if some S7 agents fought with them in Mission City; even that was after Lennox and his fellow soldiers goaded Simmons into standing down and following Sam's lead). I'd be more comfortable with the military as long as Lennox and Epps and some of the others are front and center.
NEST is S7's more competant replacement. After so much of the Cybertronians was revealed during the movie, there's no need for S7 because of 2 main reasons: 1. They don't have Megatron. 2: They don't have the cube.