I'm pretty sure I've seen recent magazine ads for the DQ rereleases on NDS. And maybe even one for Chrono Trigger. And also FF Anthology, Chronicles, Origins etc. back in the day.

One of the reasons I imagine there aren't any television ads for rereleases is that those ads like to attract the audience with stunning visuals and there would have to be some explanation why this game isn't on par with the current cutting-edge technology to those people who are not familiar with the first title.

Also, polnar alluded to, an older game is already estabished in history and requires less 'education' of the public to to make them aware of it. Which would you rather buy? An unhyped new game or an unhyped rerelease? Clearly the new game would not get much play because no one knows anything about it. But people arelady know something about the rereleased classic and that will at least generate some sales. Advertising is expensive and companies would probably rather spend their money showing potential customers their future products rather than their past ones.