He cheated because he doesn't like the game. He feels forced to playing it. He streamed the cheat because he's an attention seeking person. He was banned, while others were rolled back, because he streamed it and encourage others to do the same cheat(this is Blizzards biggest no no).
I only have one question regarding this whole thing. Why isn't he banned from Twitch.tv?
Cheating is never acceptable in life. Maybe when you all grow older and maturer you'll learn that cheating is bad and those who cheat should be punished appropriately.