Media buying agencies just don’t get it. They'd better start getting it pretty soon.

How people use media is changing dramatically, and the era of force-fed commercials is nearing an end.

What's taking its place--and has been for several years at least--is a dialogue between advertiser and consumer, and more and more the consumer is in charge.

Media buying agencies need to become part of that dialogue. They need to learn how to spark that exchange. Those that fail to do so will face extinction. Or that's the clear warning in a new study from Forrester.

“Today’s agencies fail to help marketers engage with consumers, who, as a result, are becoming less brand loyal,” writes Peter Kim, a senior analyst at Forrester and author of the report.

“To turn the tide, marketers will move to the connected agency, one that shifts from making messages to nurturing consumer connections.”

The forces killing off the old system are twofold, and one is the explosion of media options that make no one medium a must-have experience. It's the end of mass media in which advertisers could push out their message and consumers were forced to accept that message as the price of admission.

Nobody’s a captive audience anymore, argues Kim. Expensive ad campaigns across mass media no longer work in this new media landscape.

Pushing out messages has become particularly ineffective in reaching a generation that's grown up with social networking sites, videogames, interactive television and video-on-demand. They use those media as they please, often skipping commercials.

The other major force of change is the internet experience that allows consumers to respond and react to those messages. Though initially threatening--do we want our competitors to know how little folks think of our product?--it wasn't long before shrewd marketers saw how this backtalk could be harnessed for good.

In listening to these voices, they saw that some voices stood out. They were the ones others listened to, the influencers. In effect, the internet created for marketers a listening post from which, for the first time, they could listen in on what's long been recognized as the most powerful form of advertising of them all, word of mouth.

As Kim sees it, the new model is all about media agencies capturing the hearts of these influential people--bloggers, for example--who can help them create ad messages that resonate with their friends.

Kim suggests agencies need to become something of a hangout where agency people and regular Joes talk about products and ads.

This is not a new idea. It's been around since the early days of the internet.

Putting it to work will prove to be a huge challenge, going as it does against the fundamental notions of mass-market advertising. Agencies make their money creating ads and spending great bundles to buy ads across many media.

But as Kim observes, while it benefits agencies, it isn’t doing much for advertisers, and that failure to deliver will force agencies to change.

“The talent and processes [in] creative and media agencies focus on delivering work efficiently for above-the-line media with large audiences and large budgets,” writes Kim. “As new media grows and asks for agility and speed, agencies can’t expect a quick fix of widening capability gaps.”