My biggest complaint with GW 1 is how the game pigeonholes players into playing certain profession/skill setup. The game has been out too long and people figured out the best team/skill setups for each dungeon, and this leads to people unwilling to run normal groups, instead only willing to run meta builds:
For example, I was mainly focused on playing my warrior when I started and warrior is a dps profession taken for Hundred Blades skill and it's only taken mainly Fissure of Foe and sometimes The Deep (2 out of 5 elite areas), the rest of the time, you either 1) switch to another character of appropriate profession or 2) you don't get invited or 3) beg your friends/guild mates to take you and make the run longer than normal.
To people that like to focus on one main character, this is kind of like Vanilla WoW where if you are not a warrior, you didn't tank, except this is an even worse in GW1 and I hope the same will not happen in GW2.