The whole damn movie is one big Idiot Plot:
- Let's recap Dark of the Moon. Humans decide that they don't need or want the Autobots anymore. Decepticons offer a peace treaty to humans if they exile the Autobots. The Autobots let the humans think they have agreed to be exiled. Decepticons immediately go back on their word, attempt to enslave humanity, only to be stopped by the Autobots and several military teams who personally witness the Autobots' heroism.
- In T4, the premise of the movie starts with, humans deciding that they don't need or want the Autobots anymore. Why are we here again? It's already been established in the past movie that a) all alien robots aren't alike, b) the Autobots have good intentions toward humans, and c) other humans are willing to vouch for this. Why are we at the point where humans are going around killing various Autobots under the excuse that "they're all like that"? The attitude seems to be that humans despise Autobots for the massacre of Chicago, with one person in the movie out and out saying that this was his motivation. Didn't a dozen or so highly trained military soldiers witness the Autobots saving the world? When Congress passed this law making it legal to declare a pogrom against Autobots, did not one of these people object to it on any level whatsoever?
- In order to execute this war on Autobots, one of the main antagonists decides to ally with... an angry, evil looking robot who has thinly veiled contempt for humans, but promises to give the antagonist what he wants and leave the rest of them alone. This doesn't work on 2 levels: 1) Once again, didn't we learn from Transformers 3 that the Autobots are good, and angry robots who talk about killing Autobots while openly hating humanity aren't to be trusted, regardless of what they say about leaving humans alone once they have what they want? 2) The motivation of the bounty hunter robot is to "clean up the Autobot and Decepticon" mess. Why would said bounty hunter, in return for being assisted in capturing and killing the robots who are disobeying their master's orders, give humans the materials needed to make thousands more of these robots, especially when said humans demonstrate that they now CAN make more of these robots, even better than the originals?
- Speaking of the controversy over "masters" and "creators", where did this concept come from? The whole concept of T1 was that it was the Allspark that created robot life, not any creators. Even if it was assumed that the Allspark was just a tool for Sufficiently Advanced Aliens to create the Transformers, there's a line used by the bounty hunter, to Prime, that basically goes something like this: "of course you have creators. Do you think you were born? No, you were built." How would Prime not know if he was born or built? How would he not know how robot reproduction works? Does Prime not have a mother, father, relatives, that sort of thing? Even if it didn't work like that, wouldn't he have witnessed robots being created by the Allspark? There's this big reveal over the Autobots and Decpticons having been made, which doesn't work either way you look at it - if the robots were created, then no one would know better than them that they are unable to reproduce without their creators. If the robots were made by the Allspark/otherwise born, the statement is just a flat out lie.
- Apparently, in T4, civil liberties have gone so far down the toilet, that various government thugs can kick in the door, and shove guns into people's faces, and even kill them, in the name of finding good robots who explicitly don't kill people, and are known to defend people. Jack Bauer isn't this fixated on torture.
- At the end, it's shown that Optimus Prime is capable of interstellar flight without a spaceship. Indeed, so are the other Autobots - we know this from the previous movies. So, why are they staying on a planet waiting to be hunted down by various humans? Given the human level of technology, the Autobots could have avoided the whole mess by simply camping out on Mars.
- It's implied that Optimus can fly because he gained a power-up when he grabbed his new sword, his arm panels reconfigured as he was pulling the sword and in an early draft it would've recolored his armor silver. If Lockdown is carrying weapons that can do that, why are they just out in the open?