-No tanks or healers
-Release dungeons do not require any teamwork or communication
-No factions
These things give the game the largest possible pool of players to form groups from, and the group content is perfectly suited for the anonymous, zerging tactics that LFD encourages. I can see how trinity games that have more strategy in their dungeons might have some drawbacks with LFD, but what is the downside to it in a game like GW2?