In Guild Wars, Guilds are very important now days
Since the introduction of heroes it is so hard to PUG (Pick Up Group) later in the game.
While heroes are not a bad thing they have really killed the PUG.
Some mission and quests can only be done with REAL players
I have waited for days in some towns for enough REAL people to show up to form a party.
And that is where GUILDS come in.