The Zombie Dragon Troll fixates so much on Zombie Dragons and being Hardcore because his friends left the game after Wrath of the Lich King or Cataclysm.
What is the common element of both Lich King and Cataclysm? They both had a lot of dragons believed dead/who were dead but brought back to life through some form of undeath (Sindragosa, Deathwing, Nefarian, Onyxia, etc.), which is incredibly cool in itself. But one aspect that is commonly criticized for both games is that they made the game too easy after a point. Wrath received this criticism heavily due to the existence of the Dungeon Finder and the game's content feeling too easy after a point, while Cataclysm received criticism due to the existence of the Raid Finder, which was seen by many as dumbing down the content after the "return to form" of the first two patches. With that in mind, Zombie Dragon Troll's friends, at least to him, left the game around this time span, either because they felt the game was too easy or for whatever other reasons they might have had, with only Zombie Dragon Troll remaining. And because he doesn't really have any friends outside of those people, he became obsessed with trying to bring back those friends in a subconscious way by trying to make suggestions that he thinks would bring them back, like making the game more hardcore or adding in the things that he thinks had brought them together, like zombie dragons.
The Troll that told Kagon (The Go Guy) to go and spread his wisdom to Azeroth was trolling him in a different way.
The troll claimed to not be there to troll him, but in reality he realized that Kagon was too smart to fall for his usual tactics. As such, he changed strategy by instead appealing to his intelligence, pointing out how his wisdom was not being heard by enough people and provoking his ego by "suggesting" that he go and try to spread it. The thing is, the troll knows for a fact that this is a fool's errand, because a large chunk of the game's fanbase is full of people with nonexistent common sense, mixed with a healthy dose of arrogance and lack of self-awareness. And the reality was that no matter how wise or smart the Go Guy was, he could not possibly convince that many people to take him seriously, especially given they barely cared to figure things out even before he showed up. Combined with the Go Guy's own Insufferable Genius tendencies, and his rage at the sheer stupidity he'd be dealing with, and the breakdown was inevitable. And thus the troll pulled off the biggest trolling attempt of his career.