Just watching as an interested outsider for all these years and partly based on the paper quoted above, much of Google's early energy and innovation was based on the simple idea of extending and applying knowledge of the new field in service to users.

When that focus shifted to exactly what Page and Brin had criticized themselves in 1998, we can clearly see that it's not the interests of the users being served anymore.

The decline of 20% time appears to go hand in hand with this shift from the focus on the user to focus on the advertiser and other interests first. I'm not claiming direct correlation but it's not a stretch to say there might be some connection.