You can declare that rock music was great in the 1960s and 1970s; and that it was good in the 1980s; and that kind-of-sucked in the 1990s. But can you demonstrate it? I think I can, with the following charts.
(They are based upon conclusions from this very great article by J. Eric Smith with further analysis of my own)
First of all, Smith’s essay is a highly amusing read and his conclusions are very reasonable. After some extensive comparative arguing, the author produced a a critical “stratification” of 79 best-selling rock bands which we can use to compare the relative strenght of each epoch.
Smith has great taste and reasoning skills (look at his explanation on why Beastie Boys is worse than Bee Gees for example) but perhaps the most remarkable decision was to include only rock bands that released at least one album that was certified at least five times platinum by RIAA. This very high threshold is really great: we have a diversified and representative group of 79 best-selling and really popular bands.
How I grouped the 79 bands: those first “hors-concours” 15 bands that were iniatilly discarded by Smith were defined the “Good” bands in this analysis. The 32 less-bad bands that “lost” in the first round were considered “Average” bands. All bands that won the first round are grouped as “Bad” bands.
For these bands, I looked for all of their 5x multiplatinum albums. The 32 “Bad” bands released 52 5x-platinum records, The 32 “Average” had 62 5x-platinum records. The “Good” bands released 56 5x-multiplatinum records. Then, I matched each of this 170 albums with their year of release. In the charts,there are only 162 albums, as I disconsidered releases after 2000.
My assumptions might be oversimplified and of course controversial, but I guess they contain some truth.
The analysis is clear: good bands had a successful (yet declining) run between 1963 and 1980. The first half of the 1980s and the second half of the 1990s were very dismal for good bands. Average bands had a growing importance and had a commercial peak in the first half of the 1980s, with 15 albums. Bad bands had a record of 17 albums in the first half of the 1990s. In the whole 1990s, bad bands had more albums than average and good band combined.
The full spreadsheet is here.