I'd like to point two important areas in which this add-on is essential:
While it's still a very useful plugin, I'd like to offer this to refute those two points:
1) If you haven't got enough material to make an electric wrench, you're not going to have ANY expensive machines to risk. The worst thing you'll have broken is a basic machine. Repairing it isn't even as expensive as making an electric wrench.
2) Any time you're wrenching multiple machines, odds are good that you'll be near a source by which you recharge your gear. Again, if you can't yet afford the energy storage to easily recharge, you probably don't have much to lose anyhow.