Is (travelling) lightness a function of more developed technique and the awareness that you can't capture every shot, every time? I used to take everything - two bodies, a couple of lenses, a flash (just in case), a light meter (despite the the camera having a perfectly accurate one), never used filters still in their packaging etc. Now I either have a pocket point & shoot digi machine which can do almost everything (to a degree) bought off the Bay for £20, or the big Leica or Blad with a single lens. If I miss a shot because of kit limitations, so be it. And in 20-odd years of snapping, I can hardly remember the composition of a missed shot. They seemed important at the time, but now? No, I can't recall a single one.
A Leica R8 and a big chunk of glass and the Blad and an equally heavy amount of glass can't really be classed as travelling light, but a single body and lens is, comparatively, for me, a light travelling companion, capable of taking at least 95% of what is likely to be of interest on any given trip.