3. The World Actually Knows/Remembers Transformers Exist
Forget the whole we need to keep the Transformers secret from The Public" angle that the first three films thrived on; as comfortable as that cliche is, the credibility of such a ploy is already strained to its breaking point. (Secret Transformers on The Moon? Really?) Going into a new trilogy, some things need to change in order for the show to go on. What better way to start off a new cycle of films than with something that would take existing canon in a new, more refreshing direction? In this case, we see humanity not only fully acknowledge the existence of Transformers, they downright hate them, which probably isn't a surprise, considering the occupation and devastation of Chicago in the third act of Dark of The Moon, but it's a direction that could have easily been taken two movies ago. By making the Transformers public as well as private enemies, it amps up the paranoia factor for our heroes. Anyone could be a threat, anyone could turn them in, and anyone could take them out at a moment's notice. And you thought it was scary enough when you couldn't tell what devices were sentient and which ones weren't.