The icon was never part of the original plan. It was put forward by the industry as an interim step, because there were some real technological difficulties in bringing the V-chip online. It was new technology, and in the national trial we undertook there were a number of bugs in the system that came to the fore.
I think what's even better than keeping the icon up is that on programs that are intended for adult audiences, most broadcasters now repeat viewer advisories when they come out of a commercial break. Every time you come back to a program from a commercial, there is a very clear description of the content of the program, and it provides a cautionary warning. The broadcasters are very good about doing that.