As you know, I love me some NVH hot mess 4 cylinder engines.
I like looking down and thinking just for a split second before shifting "damn, its really doing 8500 RPM".
Clearly the S2000 was a raging success--NOT--and a V6 would likely have dramatically increased sales, had much better NVH and torque delivery, and been more "muscley". My experience with the S2000 was that I had to work it too hard to extract the power. A V4 would be a similarly idiotic design to that of the rev-it-to-hell I-4.