Quote fromReading that tumblr was rather interesting. But I believe using that to teach anyone above 2nd grade would be stupid. People would build inappropriate things, swear, grief, trap, and basically do all sorts of terrible things. Not to mention not learning anything. It does not require much intelligence to play Minecraft, hence all the troll threads.
Even using that to teach 2nd grades would be a push. That is a rare teacher.
Doesn't quite explain how we get to play with creative programs in Elementary. Then again, it was a reward for good behavior and prompt assignment completion, which seems to be more reasonable that try to "teach" with it.