After about Frost Gate or some such arbitrary point, it becomes more and more important to group. The great contradiction here is that the people who you see in town looking for groups are your opponents in this game, not your allies. These are the bastards (said affectionately for emphasis) you will meet in the arenas and fight to the death. So helping them complete a mission seems... wrong. Asking them for help seems even less smart.
This has really lead to one main problem with the game right now: people ditching your group in the middle of a mission. It's a rational behaivor to screw the people you are grouped with in this game. It's not a nice thing to do. It makes the game less enjoyable for 5/6 or 7/8 of the population concerned. But it's rational. It improves your chances in competition against these opponents.
So... we need to group, but benefit from harming the group as soon as we're done with it. This dynamic should really be changed.
My preference of solution would be to have large alliances of guilds. There could be 10 or so alliances, and your alliance would be ranked similar to how guilds are ranked. There would be alliance specific chat, and a toggle to ignore it. Helping your alliance mates would give you a reason to help people in your group, as their future performance would reflect on you. Breaking this vast group of people into smaller groups would also promote some level of community responsability that this game is so sadly lacking.
Barring that, the suggestions to penalize a player for antisocial behaivor would get my vote. Public humiliation of the character could go a long way. Brodacasts in the towns of "Don't group with XXX as he's just shafted a group doing the mission" would go a long way to stopping this behaivor. A note to his parents would help too, but don't know if that can be pulled off.
S

