Despite the beautiful cinematography; dynamic soundtrack of the most recent film and addition of Anthony Hopkins (to save this awful movie), the entire Transformers' franchise needs a reboot. It is absolutely vile how Michael Bay has decimated the films.
Taking Unicron and suggesting he lives inside Earth is an atrocity. In the original animated Transformers movie Unicron's sentient head was floating in space. After a fierce battle between Autobots and Decepticons on Earth that concluded with Optimus Prime's death and severe injury to Megatron, Starscream with his twisted aspiration of leading the Decepticons shoots Megatron with a near fatal laser blast and boots him in space left for dead. While floating in space, Unicron reformatted and rebuilt Megatron into Galvatron who himself is powerful, insane and maniacal. Galvatron was arguably worse than Megatron. You can guass what Galvatron does to Starscream.
While near death, Optimus Prime transfers the Matrix of Leadership to Hot Rod who morphs into Rodimus Prime, a reluctant leader who eventually gets his act together and puts the 'smack down' on Galvatron.
The snippet I present above is an example of how Michael Bay and company have so grossly deviated from the Transformer's original story arc. We have not seen many iconic bots such as Metroplex, Omega Supreme, Fortress Maximus, Aerialbots (they combine to form Superion), Predicons (who merge to PredaKing), SkyLynx, Rumble, Wheeljack, Blur and others.
Tom, you enjoy modern animation films, but check out the 1986 Transformers movie (recently remastered), you may enjoy the classic animation and get the benefit of understanding how far M. Bay veered off course. Perhaps the new upcoming Bumblebee film will reset the direction.