I did that on a commercial rock station in a very large market... a #1 station in fact... and the numbers tanked miserably and ruined the rest of Sunday evening's ratings, too. And the show was well done, with good... but totally unknown... songs and artists.
The problem was that most of our target was over 30. Their interest in new rock was minimal, although we played one to two currents an hour and lots of stuff from the last decade. But all new stuff in a show just was not appreciated.
New music shows, like 1,200-song playlists, seem to be the kind of thing listeners say they want to hear, but when one is offered to them, most of them try it briefly then don't listen again, going back to familiar fare.
There's a longstanding parallel in the newspaper business. Readers keep complaining that there's too much bad news in the paper, and why don't we do stories about people doing good things. But whenever a heartwarming good-deed story makes it onto Page 1, sales at the newsstand are considerably lower than they are when the top of Page 1 has coverage of a grisly murder, a spectacular fire, or a political scandal.