I work in advertising and by far TV is the most effective tool to effectively reach a large audience.
I work on political campaigns, and that in itself is part of the issue - the trend (which I wholeheartedly agree with) is leaning away from reaching a "large audience" with an impersonal ad towards smaller audiences with more in depth contact.
The old school way of thinking about politics is that a person needed to be "touched" 7-10 times before someone's name would stick in their head (seeing an ad on TV, getting a mailer, seeing a lawn sign, etc are all "touches"). So that's where you get the piles of junk mail and ridiculous amounts of TV ads.
But there's a significantly increasing trend towards actual voter contact, rather than "touches". Instead of putting all that money into TV ads, campaigns are paying canvassers to knock on doors and have conversations, or phone bank. These contacts are much more effective (and in the end, cheaper) than the old-school "touches".