As Spoony said, Michael Bay is an attack dog. He's given movies that with craptacular plots, told to make some 'epic' fight/destruction scenes and then go home and bathe in money. He does exactly what he is told and in doing so creates movies that are fairly poor yet sell well as eye candy. Issues with his camera work or lens flare are trivial as even without these the movies would be terrible. Give Transformers 2 or Armageddon to any other director without allowing them to influence or change the script and maintain the same level of producer pressure and you wouldn't have a good movie, no way in hell would you have a good movie.
Steve Spielberg produced Transformers 2, don't ya know. Now I'm sure that had he wanted to make a good movie than the plot would have been good. Everything wrong with that script could have been removed if he had wanted it to be so but he didn't, instead he gave a shitty story to Bay and Bay was told to turn that into a movie. Roberto Orci, Alex Kurtzman and Ehren Kruger were responsible for the script and Speilberg was all to willing to let that script fly, if anything they should be held responsible for the travesty that is Transformers 2. Orci and Kurtzman are also responsible for The Island, Mission Impossible 3, Transformers 1 and the new Star Trek. They as well as all the other writers and producers behind Bay deserve more criticism than anyone else. They create shitty stories and they fund shitty movies, Bay just controls the the speed of the swirling camera.
Bay is a shithouse director and I doubt that he ever tries to make a movie in any other way than how he is told to made, but it is poor form to not look past him and claim that he is the sole reason for a movie being terrible. If he completely funded, wrote and directed his own movie than it would probably suck and you'd have reason to criticize him.
EDIT:
cuddly_tomato said:
The thing about Transformers 1 is this - it had Spielberg as co-producer. During some of the scenes you could almost imagine him on set, standing behind Bay with a copper mallet in his hand, saying "if you shake that camera one more time Michael it's lights out for you". Transformers 2 was Bay all on his own, being handed the reigns to do with as he pleased, Spielberg presumably having gone to aid George Lucas in assassinating Indiana Jones. We saw the result.
There was well a year and a month (roughly) between Indy 4 and the release of Transformers 2 so I think it unlikely that he was still working on that while Transformers 2 was being filmed. I think that if anything, Spielberg would have been absent from Transformers 1. Putting this to aside however, as Producer Spielberg has more control over the film than Bay to level that he could choose director so even if he did give Bay free reign (which I doubt) for Trans2 he is still responsible for that being a bad movie, a long with the writters.
A parallel can be drawn between Batman Forever and Batman and Robin. Both films were directed by Joel Schumacher. However, Batman Forever was produced by Tim Burton, and as a result you could see some of his attempts to keep the film actually reasonable. Without Burton watching over Batman and Robin, the film descended into a shit heap that put the franchise on ice for years (I could drop a Mr Freeze quip in there but I shall resist the urge).
Exactly, the producer has a greater control over the movie than the director. Because of this, they should take part in the blame for a bad movie. Of course you can never know for sure how much influence the Producer had so you can never fully blame them but in the case with Spielberg he would have made Trans 1 & 2 good if he wanted to. He didn't and as a result the movies suck and Bay gets the blame.