Diversity is a good thing, so long as the diverse characters have flaws they need to overcome. The problem comes in when these diverse characters aren't allowed to have flaws, because any flaws in such a character is equated with bigotry in the writer.
The older Star Treks had flawed characters. Data had no emotions, which lead to him being naive and gave him difficulty in human interactions. The episode of him trying to have a girlfriend and it being a disaster. The episode where Keiko and O'Brien got married and there was a Romulan spy on board highlight both of these flaws. Picard was a stiff, formal man with little patience for children or frivolity. Worf was too quick to use violence, naive about the difference between Klingon values and the realty of Klingon behavior, and struggled with religious doubts.
These diverse characters aren't allowed to have any of those flaws, because giving them those flaws is viewed as a negative stereotype, so they come across as very flat, and bland. They can only express feelings and viewpoints of infinite nobility in a tone of heavy sacred reverence.
In fact, the only character allowed any flawed complexity, Saru, is an alien played by a white guy. Not surprisingly, he's also the most interesting character on the show, and the only one who has any real character arc.
Ironically, these insistence on making the diverse characters flawless does them a disservice by making them bland. Worf, a character played by a black actor, is one of my favorite Star Trek characters. He was too quick to use violence, he was dour and Spartan, he struggled with religious doubts. Because of his upbringing his view of Klingons was deeply flawed. He was the equivalent of a Christian boy raised in isolation to truly follow all the charitable ways of Jesus who then encountered a town where almost the entire population was technically Christian, but everyone cheats on their taxes and has premarital sex and does all the hypocrisies most Christians engage in. You could see it in things like his interactions with K'Ehleyr where he proposes marriage after a one-night-stand and she looks at him like he's grown a second head.
Worf could NEVER exist in current writing, especially not played by a black actor. All the complexity and flaws that made him one of my favorite characters would be erased and replaced with him just expressing pure flawless nobility in a tone of heavy reverence.