Herobrine joined the game
SnappCraft: AW FUCK
Herobrine was banned by AntVenom
AntVenom: Pwned sucker.
Minecraft is also popular for how easy it is to mod its code. Mojang has even come out by saying that they support the modders. Minecraft mods cannot be compared to mods for other games because of what Minecraft mods are capable of doing to ones game. Take a look at the Applied Energistics mod or Buildcraft. These mods completely reinvent the way the game is played.
Unlike most games such as CoD. Mojang doesn't have a Public Relations department. Minecraft got popular strictly by word of mouth.
Minecraft is the most played game on YouTube. A lot of famous YouTubers make Minecraft Videos (AntVenom, ChimneySwift11, and direwolf20, to name a few).
Minecraft is also in active development, and it's likely to be that way for quite some time as Minecraft is still very popular in the internet gaming community. Each update usually adds new items, blocks, biomes, mobs, and bug fixes.
Minecraft is also known for its community. Its community is full of creative people who love to show off their awesome creations. There is also the modding community where new modders can go and talk code with pro mod developers. (minecraftforge.net, minecraftforums.net)