I believe in the real world benefits of odd object training, of which kettlebells are included. Barbells strength and power building characteristics are undisputed, but gym strength does not necessarily express itself in reality.
Well said Geoff. I very much agree. At the workout level the variability that can be accomplished in something as seemingly structured as S&S is incredible. Candidates for variance are all pieces of S&S. The warm-ups (goblet, hip bridge, and halo), main (swings, get-ups) and stretching (90/90/, QL). For example almost every time I do 5 goblet squats it's sometimes down and right up, other times turning sideways and back and forth, other times curls, etc). With the swing it can be 1 hand, two hands, alternating hands, etc. Similar variations of the get-up also.
Let's not forget all of Pavel's mentions in S&S of Nicholas Taleb's Antifragile: Things That Gain from Disorder.
It ties in to the workout level and far beyond that to the "life"level.