As I said elsewhere, I think Minecraft provides a great environment for prototyping for someone who doesn't have a background in electronics. I don't see anything wrong with this at all. I reckon the builder probably does "dream bigger", and uses Minecraft as an exercise and/or sandbox. Is there a reason he shouldn't do that?

I am curious why so many people interpret this as a sign of an addiction and wasted time instead of a purely awesome accomplishment in self-education. Few people keep "build something cool in Minecraft" as their only aspiration in life.