As you probably already know, Shia LeBeouf takes himself very seriously indeed. When he's not releasing bizarre motivational videos on YouTube, he's installing himself as an art exhibit in galleries. It's hard to imagine that he'd ever accept a part in an action movie franchise like 'Transformers' now, but he did so in the past. Needless to say, he didn't like it very much.
It wasn't so much the first of the 'Transformers' films that irritated LeBeouf so much as the second one, which he felt had a weaker script. While noting that it was popular with viewers, LeBeouf said that he hated working on it, and that it lacked heart, closing with the line 'it's just a bunch of fighting robots.' He might be right, but isn't that the point of 'Transformers?' His disdain didn't stop him taking his paycheck and coming back to play the part for a third time a few years later.