As I've said before, the supply-demand equation is out of whack. The only way to balance it is to either restrict supply or increase demand. The way that gets done when demand cannot be artificially promoted is with cost controls of some sort. If there is any demand at all, it will be found when price point is married to perceived value. But I do not think that it is appropriate in every instance, and I'll tell you why.
Direct response is only one option.
Use of advertising as a sales channel is only one way to affect an advertiser's bottom line. Regardless of our ability to use the Web and read causal relationships between our advertising and its effects, we cannot dismiss the fact that there is something to be said for advertising that does not result immediately in an action. Media results are not predictable. That is, we can guarantee the advertiser the CPA but not the volume. An advertiser might want a demonstrable CPA projection, and it is possible to produce that.