I'd tend to disagree, with no government plot for the introduction of megatron something could have been done with the decepticons and knocked out 2 birds with one stone. Sam already had his place in the movie as the owner/whatever of bumblebee, fish out of water in the autobot squad, other meaning could have been easily applied. The government didn't really 'add' anything to the movie. The sector 7 segments I suppose weren't horrible, but I feel they detracted from the movie as a whole, and the hackers were 100%, unadulterated garbage, and never should have been in the movie.
Sector seven, at the very least, could have/should have been reworked.
The biggest problem with not introducing the decepticons isn't that you don't get their story, it's that it cheapened the final scene by making everyone indistinguishable. I didn't know who was doing what most of the time, partially because I remember nothing from the cartoons and partially because the characters 'introductions' consisted of their name being mentioned once in passing. They looked too similar and all kind of blended together, the only memorable sequence I have in my head from the final scene that was good was (Jazz?) creatively avoiding missiles, and starscream wtfpwning the jets. I don't know any of the other decepticons names except Megatron, who was played off horribly.
Megatron: You're just a shitty, slow human, I'm an uber-fast space robot, but for some reason I can't catch you. And when I do catch you, instead of doing something I'll sit here and have a staring contest until Optimus Prime gets all Clint Eastwood on my ass.