Jim,
Thanks. I'm sure it would be faster on a crowded day. But I'm guessing that more people don't climb the outside of the cable section because it's way out of their comfort zone (consider how many people freeze up even when using the cables) -- many, if not most people who do the cables probably have zero climbing experience (and some probably have little hiking experience), which would put such a climb beyond what they could or should be doing.
RP - Just looked at that picture (nice photo angle, by the way). I can see all kinds of hand and footholds going up the left (south) side of the cables. It would be kind-of a zig-zag route, though, and would take you out and away from the cables most of the time. See your picture with my red route line added
here (you will need to scroll around to the left of the cables to see the whole picture, since it is in its "original" size, to better see the route details).
CaT