Edwin clarified my thought on thinness; the bombs were there, but a thin high end sound persisted as he went through many different basses during that time. And the changing Sound system too, especially when they started getting into the digital system.
In terms of interaction, the changing keyboards can almost define the different sound eras of the band. There is a distinct break in the sound and direction of the band with each change in keyboard player.
I agree that Keith contributed quite a bit to the rubber band sound. In my mind he was often a catalyst for starting and maintaining the long free jams.
Nothing against Mickey, but I think adding back the second drummer limited their ability to turn the corner and build some of the freer, spicier, exploratory jams. But then, the band became more refined and bounded in their approach over time as well.
And for a planet that is 4.5 billion years old, a few decades isn’t that ancient!
