One thing I have been thinking a lot with more recent action films is that many have lost the 'battle narrative' - that story within the story that makes a big end battle interesting. An example of an excellent battle narrative can be seen in Braveheart - here we know what the heroes are up against (superior numbers, horsemen) and we have an idea of what they have going for them (bravery and wits). Finally, we have a hint of the chink in the enemy's armour (the arrogance of the commander). The enjoyment in watching the battle comes from watching the characters deploy a plan that takes advantage of their assets and exploits the weakness of the English. Wits --> Infuriating the English so they charge, using long pikes to impale the cavalry. Bravery --> Standing at the front of the line to face down the charging horses.
'Transformers' shows how recent films are bumbling around and messing up their battle narratives. It was unclear just what the characters had going for them other than that one was a 'soldier' and one wanted to make a 'sacrifice' at some point. It was unclear just what weaknesses the Decepticons (bad guys) had, except that they were vulnerable to certain "Sabre Rounds". Instead of using their assets to create coherent plans that exploited this weakness, the characters ran around almost as if they were in a cartoon, cooking up increasingly ridiculous things to do - like sliding a motorbike under a Decepticon and shooting away with a shotgun (after we've already heard that normal rounds don't work.)
This is not about plausible and implausible. Starwars had an interplanetary farmboy flying at a 'deathstar' but we knew what he had going for him (mad pilot skilz, rudimentary jedi training) and we knew the weakness (a small thermal exhaust port only 2m wide). Our enjoyment was not only about the visual effects, it also came from watching a plan unfold that referenced what we knew about the characters already.