I was thinking about this because we had a situation this weekend in Karazhan where someone got a little hot under the collar from the tone and warnings of our raid leader. He was slightly undergeared, a little inexperienced, and he messed up a few times. When he did, our raid leader told him what he was doing wrong (using slightly colorful language). You could tell from his voice that this player was frustrated and a little embarrassed. You could probably also tell those things from when he made a comment about the raid being like living in a Machiavellian state. While a lot of people would just be damn impressed that a World of Warcraft player not only knew but used the word "Machiavellian," I thought it was more interesting that he was kind of correct.
One of the central ideas of Machiavellian theory is that cruel actions are sometimes necessary for leaders and that good can come of them. What characteristics should necessary cruelty have? "It must be swift, effective, and short-lived." Yelling at someone in vent is fast, informative, and it has just enough sting to motivate you not to mess up again. A raid leader's job isn't to hold your hand, dry your tears, and give you a cookie to make you feel better. It's to get the raid done as quickly and efficiently as possible, with minimal snags, minimal drama, and minimal wipes. Nobody likes a six-hour raid, and that's exactly what you have when people are making mistakes. Especially on raids that your guild has on farm status.
On the other hand, that Machiavellian style of thought isn't exactly held in high regard. There's a reason why your initial reaction upon hearing the word is decidedly negative. People might not like six-hour raids, but they also don't like people on a power trip who go out of their way to belittle and anger other players. For most raid leaders, that's certainly not their intent. Like a coach or a drill sergeant, the rough exterior is there to motivate people and kick everything into gear. Sometimes, nothing gets done without someone applying the spurs. Especially when it comes time to farm necessary materials for consumables or do some reputation work.
It can be a tough line to walk. Most people don't really like being hard-asses, but if the raid starts at 7:00 and you only have half your raid force present at 6:55, you don't want a timid person with a gentle voice coaxing people into getting a move on. You want someone who is going to be a jerk, lay down the law, and spark a little action. You need someone giving orders, and people need to respect and obey that person if you don't want to waste hours of your time and lots of in-game cash. It's important that people understand that it's not personal if you want to avoid guild drama (and you really, really do). The really good leaders know how to toe that line carefully enough that they can keep people motivated, reprimand people for mistakes, and not piss anyone off so much that things blow up in the process.
While I don't doubt that there are guilds out there which can take care of business without a strong and sometimes abrasive leader, I would bet that they're few and far between. I'd imagine it's pretty hard to keep a serious raiding force whipped into shape without a presence like that in the raid. It might not be nice, and it might not be pretty, but it gets the job done. Would you rather have yourself a raid leader who keeps quiet when you mess up because he doesn't want to embarrass you, or would you rather have a shiny new epic weapon because he yelled at you last time and this time you remembered and did things right? I know which one I'd pick.
You might catch more flies with honey than with vinegar, but you use vinegar to slay dragons.