The thing about making these films darker is that TF is a franchise of toys to children. If you’re going to make a story about these characters, there should be a bit of lightness so that people of all ages – from kids to adults who remember them as kids – can enjoy them. Bringing in all these dark elements to make it more adult-like doesn’t really do much to improve the overall story and film.

DOTM was pseudo-dark, semi-dark and quasi-dark. It was the Diet Coke of darkness: one calorie off. We had the following elements toned-down for the sake of catering to all ages:
- assassinations committed offscreen
- a plan that worked at cross-purposes (bringing Cybertron to Earth through warping would have destroyed Earth... so why keep Earth’s population as slaves if they’re probably not going to make it to the next year?)
- an execution scene that was executed pointlessly (why waste time rounding up Autobots when you can just kill them on the spot?)
- an electrocution scene that was tamer than it should have been (in fact Dylan was going to be grilled to a crisp by the pillar)

The only really dark parts were the Washington/Chicago massacres when the Decepticons were unleashed on an unprotected Earth. That was some hardcore doom being unleashed on Earth, and acceptably dark enough for these films (TF is war, after all).

 

Honestly there needs to be more autobot deaths in tf4 than tf3