He is right - for those who do look forward to these movies just to lambast them. There are other critics though, who do not seek to hate them for the sake of hating them, as you implied. These people may not be born filmmakers, but it's their duty to call out the nonsense that's being spoonfed to them, usually (but not always) made by the Hollywood template-generating factory. Hence, the frustration.
See, the best critics are the ones who champion the underdog films, the one which suffered from under-marketing or getting misunderstood by other critics. The late Roger Ebert, who mostly judged movies based on their genre conventions and filmmaking skill, and not by an overall spectrum, championed then-unknown films like "Better Luck Tomorrow", giving director Justin Lin a Hollywood career in the "Fast and Furious" franchise. That's not to say he was right all the time - he hated films like "Death Wish 3" and massively missed the point of "The Hitcher" (1986), both of which I greatly enjoyed. It's also a matter of personal preference at the end of the day.
I'm not a Bay defender nor hater, in fact I think he is a notable action filmmaker, and for the most part his non-Transformers outings have been pretty darn good of late, with the massively under- appreciated black comedy "Pain and Gain" and last year's intense "13 Hours" more than proving that he is a capable filmmaker with a weird, wonky but undeniable auteur style of his own. I didn't even hate the last four "Transformers" movies.
I hated this one.
Not because I was vindictive, no, but like the masses, just wanted a brainless, fun time at the cineplex with some buddies. Even in Bay's earlier action stuff, there's always something to be appreciated, whether at the audacity of the "tasteless" humor, or the sheer energy of seeing a Hong Kong ferry being airlifted before crashing onto Kowloon in high-destructive style.
Here, Bay is going through the motions, and this will be boring even to the common moviegoer. The jokes are lazy, the action sequences are repetitive, the twists are predictable and can be seen from a mile away. How many times can you see giant robots clanging and banging against each other? How many times can you hear the cliché machine spewing out lines such as "No one gets left behind!" or "I'm not gonna leave you!" It was a boring, $200 million cartoon episode (a bad one) with no heart, no soul, and at 2 and a half hours with about $20 spent on a ticket and popcorn, it is unforgivable. It was all sound and fury, signifying nothing. I owe an apology to John Moore for "A Good Day to Die Hard" after watching this boring, poorly edited mess.
In conclusion, there is no shame in liking a film others hate, or vice versa. But don't assume all critics are out for blood. For the ones who are forced to sit through this to fulfill their editor's assignment and get paid, the frustration is understandable. It's their job. It's dirty, but someone's gotta do it.