From my BWE experiences this weekend, I wouldn't really say pickup groups are that horrible. In the first few missions, yes they can be, but I think many of those parties are made up of inexperienced players. I hope so too.

However, this seems to sort itself out after the first three, four missions or so, since pretty soon you face missions you must team play in to win, and the only players winning are those who team played good enough. Already when I was starting to get to the mountaineous areas in this BWE I was seeing a dramatic difference in how people played. We were laughing and having fun at picking torch carriers, LOL'ed at being smashed by catapult blasts and having exploding barrels dropped by people not knowing what it did and me shouting "run!", and basically every single one of us six party members had a great time. One of them kept saying "oh man, I can't wait for this great game to be released!" and people in our party started discussing which real life school they had been studying in after realizing they were from the same city. It was really an uplifting experience after playing, say, the Northern Wall with people until giving up and just playing with mercenaries.
So this game actually being unusually HARD (to players not teamplaying well it's pretty much gaming hell) for today's games, may actually save it quite well at least. If you compare to e.g. WoW where the "toughness" may come from finding enough hours to play on per day to advance to level 32.
If one is guildless it will of course help a lot to get in contact with a fairly large GW guild/community. A player seeking for guild membership can check in the Guild Auditorium here for good guilds with free spots, and with the guild cap at 100, a whole lot of friendly people can get together for both PvE and PvP.
But yes, with a game with no fees like this, I'm preparing for a similar community in general as the one in Diablo II -- not exactly heaven to role players. However, I kept playing Diablo II for very long as I still enjoyed the game for what it was and what the community I'm member of was. Guild Wars also has the same advantage as Diablo II in that you play PvE in instanced areas. And in PvP I'm not really caring too much for guilds with bad morale. Yes they can be annoying if they win and act arrogant, but the fun of beating some extremely bad losers can make up for it.

I remember once that we did that and I could almost hear them throwing their keyboards in the walls; they had taken out their victory and started insulting us in advance and all...