My mistake -- my wording was a little poor. Minecraft is an environment that allows people to be very creative, but it isn't efficient in that process. When I say "meaningful" I meant it more as a comment that I wish a development environment would exist that was as engaging as Minecraft (like a game!) but as efficient as a programming language like Python.

Because Minecraft is purely a game, it limits what a kid can accomplish from the start. A kid can only interact with their creations through the game itself, which is fine, but could it be better?