Henry, I have to side with Jay on this one. I believe grounding aluminum siding would be a good thing. Here is why. Say , for example , the aluminum siding is ungrounded, and just floating. Now say one of the wires passing through, or near it rubs bare, and contacts the siding. Now the siding is energized at 120 volts. Since it is floating and there is no path to ground, no fuse or circuit breaker will trip and it will stay that way, unnoticed. Now along comes Joe homeowner standing on "true" ground and touches the siding; z-z-z-zap. Also the energized siding may get to arcing with some other partial conductor, and then it becomes a fire source.
Incidentally, Henry, your experience with the drill indicates why those older, non double insulated drills with metal housings always had a three prong grounding style plug. When plugged into a properly grounded outlet, the shorted drill would blow a fuse or circuit breaker and protect the person holding the drill. So many people used cheater plugs, defeating the grounding ideals , that double insulated housings, and ground fault current interrupting (GFCI) circuit protectors became common. BobB