That a significant proportion of advertising involves deceit, coercion, and captive audiences says a great deal about the nature of it. The First Amendment codifies the right to say what you want, to print or otherwise make public your thoughts. That doesn't give anyone, or anything, a right to
force their ideas into the minds of the public or a subset thereof. And while advertisers are not quite yet forcing anyone to consume their product at the proverbial "barrel of a gun" they are far beyond the norms of human communication.
It is not acceptable for a stranger to come up and start shouting at you while you're trying to read, or hold a conversation, do your shopping, or put gas in your car. So why is it somehow acceptable for advertisers to do so? Would you want to pay for a course of instruction, some unknown percentage of which was not instruction, but was actually conducted at the direction of unknown others, who, with no regard or concern for your life, liberty, well-being or happiness were trying to extract wealth from you? Yet that is exactly what happens with much of our media-mediated experience of the world.
I think the underlying changes in the technology of communication have allowed advertising to grow without sufficient thought on whether such expansion was actually a public good. Like license plates - the impact of which changed radically when the government could, thanks to advances in technology, use them to monitor the position of virtually all vehicles over time, instead of being forced to physically look up who owned what vehicle - the explosion of media over the last century has been accompanied by an immense shift in the impact and capability and intrusiveness of advertising. And it's legality needs to be reassessed in that light.