Transformers is a deeply silly idea.
But then, so is the idea that for some reason a Norse God shows up in modern America and teams up with a guy who's good at archery and this other guy who dresses up in patriotic S&M and then someone who is, in effect, a guy in a robosuit and anyway they go fight monsters or some shit like that.
...in other words, yes, Transformers could be done better. If something as inherently ridiculous as Avengers can (allegedly, haven't seen it) get a good movie, then so can Giant Robots Punching Other Giant Robots. Not to be confused with an assertion that Transformers has ever been any good, as much as it's a childhood memory of mine.
Silliness has nothing to do with it. No CG-ed punching robot will ever be as charming as Downey, as soulful as Ruffalo, as earnest as Evans, as regal as Hemsworth... etc.
Transformers is an ugly and boring idea, a nonhuman-toy commercial, pure and simple. But given how crappy Bay's movies are, the longer he wastes his time on them, the better, I suppose.