If it ain't broke, don't fix it.
There was a discussion of this a while back when the 3 deaths had occurred (two were in off-season with cables down). The system is pretty self-regulating as it is.
People who don't like crowds, don't go, or try to go when it's not crowded.
The cables are a narrow, two-way street, with the slowest ones being the limiting factor. People who see that will either wait, or not go up. (or, as the moron did posted above, just climb up elsewhere, turning back or adding to the Darwin pool 8^).
The long hike to get there is a deterrent on its own, for many.
Just seeing the cables, or fear of heights, is a deterrent for many others.
For those with some technical skills, they can skip the cables and use the Snake Dike route.
Lightning and thunderstorms reduce the number of sane people going up, when they occur. For the rest, when there are signs at bottom and top warning of the danger, why worry about it?
Really, Half Dome crowding is only a problem for people who must go in the busy summer season, and especially if they leave the trailhead at a 'convenient' time.
There were quite a rash of articles about climbing HD within the past couple of years, which I think caused a lot of people to go who otherwise wouldn't. If the publicity subsides, maybe the traffic will lighten up a bit.
So hopefully they'll just leave it alone unless there begin to be real problems, which there aren't now.
Gary
Yosemite Photo Galleries: http://www.pbase.com/roberthouse/yo