Giving a closer attention and interest to Minecraft and the diverse reaction this game imply around me, I started to research and think a little further about the game.
First I was happy to notice that the parents of the closest friend of my son did remove the game from the computer of their son. Interesting to note that even if they did buy the full version in the first place, they noticed the negative impact the game had on their son and reacted promptly.
One of them, who is totally computer literate and like to optimize his 2 sons's time, simply explained to them how that game was a simple waste of time. As his son was tentatively arguing about how nice it was to build stuff with that game, he replied something like " if you want to build something, take some wood, hammer and nails and build it. A game does not build anything."
Basically I would say that Minecraft is using a few trick, first it is using the popularity of Legos, kind of copying the building side of it but in a virtual world.
Second, it is using a very well know aspiration of teenager, the one for freedom. it does give the player a sensation of infinity and in so, feeling free.
Third, as a lonely world, even a total freedom, would be rapidly boring, the game is a multiplayer one. This way, kids "meet friends" in this virtual world and satisfy their need of belonging to a group.
So what is happening? those kids love to get together with their friends and play, this is not new. The same way they used to play in the street with their friends, they are now "free" to play with them but in a virtual world. However, all the different games and discussion they used to have in the street vanished as their only subject of communication and exchange is now around the game itself.
Even worse, they make "new friends" that they will never meet in real life! Everything is virtual, everything is an illusion, except their feeling.
And they totally dislike those who do not belong to their minecraft world... tell me about tolerance, open mind, curiosity...