There are bots for Minecraft, ylt (youlikethaaaat) is making/has made one on D3's server. It can talk through commands and walks and stuff. It also unintentionally noclips (no collision programmed in so yeah).
If someone was really going to make a USEFUL robot, they could just have it spawn wherever it's needed and warp around placing blocks at record speeds breaking the sound barrier and what not.
Repair bots that can dynamically repair things as I've said before would require some really extensive programming. If it was repairing something static like a specific building then it wouldn't be such a problem.
This looks cool. When I see him I will make him follow me to some griefed structures (even if I need to grief my own things)
When I read this, I imagined him following you to some structure, and you begin to grief it so you can watch him repair.
Friend's eyes glow red.
Two seconds later you're banned from your own server and Friend has automatically joined every active server and told everyone that "ACCOUNT NAME SHAILSTSPT IS DESTRUCTIVE AND DANGEROUS. RECOMMEND BAN."