The problem with Guild Wars 2 is that instead of having one main philosophy that carries throughout the whole game, it has multiple philosophies that interfere with other parts of the game as a whole.
In most aspects of the game, when you see another player in Guild Wars 2 it’s a good thing. Someone to kill with, someone to help, someone who isn’t detracting from any part of your game because they aren’t taking any mobs, loot or crafting nodes. The game presents itself as an open casual game inviting everyone to come have fun.
Then you get to the dungeons and the philosophy is abandoned. It’s NOT welcoming for everyone to join in. You are hindered by random people that you meet. You don’t want them in your dungeons. They are a drain on your money, your time and your enjoyment. The dungeons take that entire open welcoming philosophy and disregards the rest of the game that people have built expectations from.
The idea of the one-shot mechanic in a game with no way to control who gets targeted by them is one of the weakest forms of “challenge”. Just waiting for the boss to decide, “Well, you are going to die now,” is never rewarding.
The argument that the dungeons are for the hardcore doesn’t fit with the rest of the entire game and how it is made. The game isn’t attracting hardcore gamers, it’s not even marketed to them. What is happening is that you have a game where you hit max level and find that all the shiny fun items are locked away behind a system that wasn’t made for you.