We all know the command /regen from WorldEdit. It basically allows you to make a region the way it was when it was first generated. I think we could use this in vanilla minecraft. With the addition of /fill and /clone, why not add /regen. This idea came to me when I joined a minecraft server that was vanilla, and the land all around the spawn was griefed. The terrain was ugly, but if the /regen command was implimented, it could be fixed! Let me know what you think below please!
Edit: The command would be like /fill, you do /regen X1 Y1 Z1 X2 Y2 Z2 and then it will regenerate the land back to it's original form between those two coords. (Thanks Over9000Guy for pointing out I should do this)