As I see it, there are only three uses of cymbals; percussive, atmospheric, and tonal. When you add to the cymbal arsenal, you are going for different tonalities, quick or short decays, or unusual sounds that catch the ear in unexpected ways (so long as you don't overplay them).
Some cymbals act as "sustain pedals." They build under the music in a way that supports it, but that is merely one aspect of cymbals. I could write at some length about what each one of my cymbals does, but I'm sure you could, too, and we ought to try not to bore each other that way, at least not without permission.
DeJohnette was not talking about using cymbals less; he was talking about using fewer cymbals. The only thing I can make of that is that he came to rely more on the drums for percussion, tone, and melody, leaving the cymbals to the more conventional role of ride and crash (wash and sustain)… with the odd china thrown in for whatever it is that we love about chinas – I find the china (or similar) to perform in all three categories - as long as it is not overplayed.
The reason I asked the question is that I have been trying to reduce my cymbals in order to reduce the number of stands I have to carry and to simplify setup. Impromptu, I can play with a flat ride, a crash, and a set of hats, but I can't do that in the music that Cupola has been writing. Every time I leave a cymbal at home, I regret it at some point in the evening.
I have reduced the setup by one cymbal and the 8ø tom… one stand down, a reduction of 25%. In order to do that, I have to choose between an atmospheric ride or the only cymbal I own whose instructions say "crash." I was hoping to leave about three more cymbal (and two more stands) behind, once I understand the role of cymbals better.