Everyday you may sit on the bus, take a moment to look round you. How many people do you see playing mine craft; I ensure you, lots. And now they want to start classes for mine craft!
I think those classes would be an absolute waste of time. You go to school for future benefit, and as far as I know, there aren't many jobs that use mine craft. Think about it, children could be using this time for social life or learning things that actually have a purpose.
It's also physically and mentally bad for you. Staring at a monitor for a forty minute period shatters your chances of good eyesight in adulthood. The bright screen captures your eyes and leaves them sore and stingy, it damages brain cells and disconnects your focus. And even worse it becomes a addiction. People start downloading the game and play it till their finally distracted by the call of lunch or breakfast. they forget to exercise and become the local couch potato.
Look at it this way, little kids are new to this world and many think they live with little square headed people because they've been given the authority of an i pod. For teenagers it's once again different, games become their life, they start thinking their careers will be the exact same as mine craft. They thin k they know how to live, but they don't.
So think, what about the children's welfare and reputation. Just think, what do children learn from this?