I love Poe, but I've never defended his actions in TLJ, because it was HIM who was in the wrong, never Holdo.
In The Last Jedi Poe did the following:
-Disobeyed direct orders from Leia to call off the attack on the Dreadnaught. This cost the Resistance many, MANY lives, and just as many ships
-Lied to Holdo when he told her he was "Commander" Dameron when Leia's last act (which Holdo points out) was to demote him for his actions
-Started a mutiny. He's damn lucky all Leia did was stun him, mutiny is usually worth a punishment far worse than that.
-Blabbed to Finn and Rose the moment he learned of Holdo's plan. And DJ happened to overhear Poe tell Finn and Rose what Holdo's plan was. DJ then gave that information to the First Order.
The reason why Holdo didn't tell anyone her plan (and also why I personally think she freaked out so much when Poe told her Finn -AKA, the ex-stormtrooper who had only defected from the First Order a couple of days before- was on the mission to Canto Bight) is because she probably thought there was a traitor or a spy on board because of the First Order having managed to track their ships through hyperspace.
Poe only really trusted Holdo when Leia explained her plan to him properly.
Holdo was an essential piece to Poe's character arch. She showed the audience that Poe isn't perfect, that the impulsiveness and cockiness we all love him for can be a REALLY bad thing in certain situations.