Why do we remember Bach and not all those hundreds of other composers of his day? I suspect it's because they, unlike Bach, wrote formulaic pieces that gave their audiences what they expected, and no more. Bach, on the other hand, used a precise, rather mathematical structure that nevertheless had wonderful arrangements and elegant melody. Listen to "Air for the G-string." It's both familiar and surprising, simple yet sophisticated. The same could be said of AC-DC's "Back In Black" both the single and the entire 1980 album of the same name. Remember many other hard rock bands from that period? Do you still enjoy them, even buying a record of them again on CD? Or how about other artists from then? Are you still humming along to that ABBA album? How about Rose Royce, or Sky? Not me. I don't even remember the last two. Yet all three artists outsold AC-DC that year. In fact, "Back In Black" didn't even make the top ten list of that year. It's gone on to sell over 16 million copies in the United States alone, however. Why is it so popular? I think for the same reasons as "The Brandenburg Concerto" still is. It's not because of the form or the genre. Its because they are both imaginative.
Listen for example to the guitar solo I mentioned earlier, near the end of "Back In Black." As the vocals are ending, Young begins in the twelfth position, high on the neck, bending from a C to a D, then uses some expressive vibrato, before moving on to bending a B to a C# before slowing releasing it and playing an A note, the chord of that bar. Then he does a pick slide and moves to the solo proper, which begins low on the neck, in the third position. The change is unexpected. Most guitarists would probably have stayed in one place for the solo, or used a couple positions at most, or some obvious up and down pattern with one or two attempts at expressive touches. But Young moves all around the neck, uses slides, bends and vibrato, while always staying within the song itself, never existing for its own sake. He plays fast and then slower, milking a note then throwing out a flurry of them, tossing in squeaking artificial harmonics like sparks. It's a tour de force not only of technique but of invention.