I too think that all advertising targetting children should be outright banned, permanently. At least, television advertising (I don't mind so much if toy companies want to run ads in print). I was probably in the first generation targetting extensively by advertisers as a child, and I can definately see the effect in later generations as the techniques were refined. The ads generally encourage children to pester their parents for stuff, ie it constitutes an antisocial force in our society. I think there would be tons of support among voters for such measures - its the kind of issue I'd almost consider changing my vote for, except ...
The problem is that it just won't fly even with massive support, and voters know it. There's just too much cronyism. The corporations would just flip a lid. Even if a bill of some sort passed, it would instantly be neutered and enforced only weakly (there are many good consumer protection laws in Ontario, but you'd never know it from lack of enforcement and general knowledge).
The revenue generated by the most gullible of audiences is just too much to pass up. And it would really be hard to define exactly what is targetted at children. There are even car ads that call on children to harass their parents ... the product may not be directed at children, but now that advertisers have realized the power of children to influence their parent's purchases, even those not selling children's products have jumped on the bandwagon.