And perhaps more significantly, DDoS attacks against Minecraft servers are extremely common. There's a massive market dedicated purely to DDoSing Minecraft servers.

In addition to its popularity, I would guess that this is probably related to the fact that the average age of Minecraft players is probably lower than the average age for most other popular online games. A disgruntled person between the age of 12 - 18 who knows they can completely shut down the fun-having ability of everyone they're pissed off at for a few dollars per hour will often feel pretty tempted.