I don't know how much to read into a sample of #1 hits, but this is an interesting discussion of how software enables a change from linear to vertical music composition. A similar change in perspective is why I've found the software Scrivener so useful for writing books; the easy switch between a vertical view of the whole manuscript and a linear view of the current chapter or section is extremely helpful.
How the Billboard Hot 100 Lost Interest in the Key Change
One of the key changes—pun intended—to the pop charts in the last 60 years is the demise of key changes. What happened?
tedium.co