There is an obvious flaw in your argument: consumers do not have the same advertising budget with which to express themselves freely, which means that consumers are not afforded "the same freedom to express their views openly".
They may not have the same advertising budget but the ultimate aim of any advertising is to get people to buy their product. If a company somehow insults me I'm unlikely to rush out and spend money on their product.
Personally I think that ASASA does a great job - most of the time, but that's just my opinion.I agree that comparative|competitive advertising should be allowed in SA.
I agree they do a good job generally fulfilling their mandate, whether the job needs to be done is another question. As long as everything said in advertising is true I don't have a problem with it.