I don't really have much experience with Kendo (other then seeing some people, and reading heaps of Kendo-World), but most generalized statements such as that (and this ironically) are usually silly. Every art represents a different aspect of styles and mind-frame of the culture and of the individuals within the systems (specifically teachers and headmasters). It really only matters what you define as the essence beforehand (and once understood and defined to ask such a question proves redundent).
Frankly I think that Japanese Martial Arts represent the essence of Japanese Martial Arts... Nothing else would really.
But then, that's just me, and vexing philosophy has always been a source of headaches.
-Amir Barak
"You get what you pay for, But I had no intention of living this way" - Adam Duritz