I'm gonna need some help on this one, because I don't really understand. The subject today probably boils down to lack of communication. I'll be the first one to admit that guilds don't really mean too much in WoW. For the most part, it's essentially a glorified friends list. It's not like the guild gets anything from downing an individual boss. Sure, members of the guild get something, but the guild itself gets nothing.
Before WoW, I played Everquest 2 for a while. It's been awhile since I've played, so things may have changed. You had certain designated members of the guild that completed writs to gain status points to help level the guild. At level 5, you got your guild name above the players' heads. At level 10 (I think), you could get guild housing. Eventually, you could have crafting tables in your guild hall, and special things to buy, etc. If one of these designated members left the guild, the guild and the player would lose the status points. I'm not sure if there were any repercussions if one of the "normal" members left.
I bring this up because we have a few members that have joined, gotten a few pieces of epic Kara gear, and then left the guild all in a matter of a week or less. And most of the time, it's without even saying anything to anyone. I've heard the gambit of excuses as well: I joined my friend's guild, you guys don't raid at the time I want (which they knew when they went on our their first raid with us), somebody made fun of my name, etc.
While I'm not discounting the validity of the excuses, what I do think is inexcusable is the /gquit without saying a word to anyone. I equate the guild aspect of WoW to a normal job. You don't just stop showing up. If you decide you want to quit, you normally give a two-week's notice. You let your boss know that you are leaving. Of course, you don't get paid in WoW or by your guild, so maybe that's not entirely the best comparison.
Maybe a better analogy would be that of a sport's team you signed up for. Think back to High School. (Some of you may only have to think back a few weeks.) You sign up for the Soccer team. You're pretty good at soccer, and your team really appreciates that you're there. You've all spent time together. You've played some games together. You've won some; you've lost some. Maybe your team even won a trophy at a tournament that you get to keep. Now, for whatever reason, you decide you don't want to play anymore. Don't you talk to your coach, your teammates, whomever to let them know that you're not going to play? You'll still see those people around the server... errr, school. Sure you can still go play baseball or whatever other sport.
/sigh. I guess a large part is due to the anonymity of the Internet. "Nobody really knows me, so why should I give them the common courtesy I would my High School friends?" Anyone else have any thoughts to help my head stop spinning about this?