In the 30s, 40s, 50s, 60s, and I am not sure when the change came but in these years hits were determined by what people wanted to hear though tastes changed with each new era. In the last decade and possibly sooner, hits have been determined by what publishers chose to be hits.   Radio programming on the more commercial stations with larger listener base is no longer determined by what people prefer. Witness the case of the "Oh Brother" soundtrack and others that achieved sales and awards without the benefit of radio. While it happens, it does not happen often.