Not sure how DJ is relevant. Poe transmitted information to Rebels onboard a ship at high risk of being captured. That is beyond stupid. Particularly when Poe already knows that Kylo can just mindrip **** right out of your head having suffered this in TFA.
DJ is the person who ultimately sold them out. I don't believe it's actually quite made clear how the First Order learns about the stealth transports, but it would make sense that DJ past that bit of information along when he was selling out. Plus, he is literally depicted as a sort of super hacker or code breaker. It would seem entirely in line that he hacked into the Resistance's networks and got a hold of the details regarding the stealth transports. And yeah, Poe is stupid and should have been locked up. What's your point there?
If you want to look at the realistic side of things. We know from Grace/Finn that people have been ditching the ship. Is Holdo going to communicate the plan when people are deserting ship in escape pods? Can those escape pods be captured and their crew interrogated by the FO?
People deserting and the seemingly lack of care about this happening is one reason why I believe Holdo's command was poor. She didn't have to communicate the exact plan, but even offering the idea that there is a plan is far better for morale than her speech about having hope.
The line is one of the problems with the film anyway. Not because it reveals anything about the speaker but because a character in the movie is telling the audience how they should feel about another character.
There's a lot I like about the film but the Poe "arc" is a waste of time. Does this guy care that information he leaked lead to the deaths of hundreds of rebels? Doesn't seem to. Poe was in the wrong, but where is this guy's reckoning? Recognizing Holdo as right and himself as wrong is a very small thing. He should be mad at himself for what he let happen. But his ego is never torn down far enough.
If it was done properly, then it wouldn't be a waste of time. But yeah, I echo your sentiment that it felt like wasted screen time since it's not even quite made clear that Poe learned his lesson. I'm pretty sure the intent was that he was supposed to have learned his lesson. If RJ was incharge of the next film, I wouldn't be surprised to see a changed Poe. But I shouldn't have to be watching the next film to know that Poe has developed as a result of what happened in TLJ.
That said, without the Poe subplot, we wouldn't have DJ. I seem to be in the minority opinion here, but I thought DJ was one of the best parts of the film. I wanted to believe that DJ was the next Han Solo or Lando, the rogue with the seemingly mercenary exterior but is actually good on the inside. For a strange moment in the film, my expectations and emotions were in line with the characters on the screen. Like Rose and Finn, I wanted DJ to pull off a daring rescue after a last minute change of heart. But he crushes it. This is the Han Solo that didn't come flying back last minute.
How did Leia come up with this idea when she was in a coma exactly? She only woke up after the mutiny took place. Preparations were already well under way.
She explained the plan to Poe, with seemingly no time to have learned about it after waking up. I suppose she could have woken up before, gotten briefed about the plan, and just hadn't had the chance to greet the rest of the crew. But that's a lot of blanks to assume. It seemed more to me that the intent was that Leia had it planned all along and that Poe's mutiny was him going against her wishes. Holdo was simply the trusted lieutenant to carry out her plans.
If there was a morale crisis, the film doesn't properly convey it except for the remark about deserters. The only thing it conveys is that Poe is repeatedly insubordinate.
Then we obviously have read the details in the movies differently. What do you want me to say at this point? The body language of the crew, such as Rose crying about the lost of her sister, likely reflecting that several people have lost loved ones, has put the crew's morale at an all time low. Slowly, one by one, the fleet went down from 3 to 1 ship. Each time a ship is left behind and blown up, the survivors are reminded of what seemed to be their pending fate. A bridge controller, someone who is in close contact with Admiral Holdo, is convinced that her own commanding officer does not have a plan that will save them and agrees to join a mutiny, a decision that no sane person would take lightly given the possible consequences of such an action. If these aren't signs that morale is low, then I don't know what you would consider them.
How do you infer that Holdo runs a tight ship when Poe never gets thrown into the brig?
I am told that Holdo is competent at something, but I don't see her demonstrating strong inspirational skills. So the other half of being a commander is being good at planning stuff and tactics. Since the First Order didn't see the hyperspace ram coming, I have to conclude that Holdo used her excellent tactical knowledge to save the remaining survivors by piloting the starship. Since she doesn't take the time to sit Poe down and talk to him one on one, it seems she expects her subordinates to fall in line and trust the leader implicitly, even if it's fairly clear that they don't.
There's this concept of military leaders that postulates that an effective leader understands the seat of his authority. If your soldiers implicitly trust you, then they will follow out your orders. If your soldiers don't trust you but you have force over them, e.g. their paychecks or the potential to line them up against a wall and shoot them for dereliction of duty, then they'll follow out your orders. If you soldiers don't quite trust you, but you can reason with them, perhaps by explaining the plan you have in mind and convincing them that it's a good plan, then they will follow your orders.
For Holdo, she seems to have misjudged the seat of her authority. She obviously doesn't have implicit trust with Poe or even someone on her bridge crew. She also doesn't take the action to put an insubordinate officer into the brig or force him to fall in line by assigning a trusted agent to watch over him. She also doesn't explain anything to him either. It seems to me that she is assuming that she has power by rank alone, which fits that notion of the ineffective military leader who expects obedience by his subordinates without ever ensuring that he does in fact have a seat of power.
Taking these two elements, it definitely seems like Holdo is a very mechanical kind of a leader. She is competent at getting ships to fly when the humans in them aren't complaining but when dealing with crew with rank authority alone isn't enough, bad things seem to happen.