I agree that the octagonal rear end is bizarre and pointless. The bigger issue I had with that tool, though, is the incredibly sloppy fit with the Truvativ bottom bracket I was using. The ID of the tool is so oversized that some of teeth barely engage with the notches. Rather than ruin my bottom bracket, I bought one of these tools which has a far tighter fit and uses a sensible square drive: Truvativ Isis Drive BB Tool > Accessories > Tools > Bottom Bracket Tools | Jenson USA