Thanks for the thought-provoking article. I think I agree with the conclusions even if the analogy isn't perfect. The connotations of under-utilization or over-provision are often negative - particularly in management - but I think as you point out are necessary in order to provide any sort of quality of service.

Qualitatively/subjectively, when I think about the times I've worked as an engineer in an "always busy" environment, I believe that I was often less productive - it's like you need space to breathe. It was certainly less rewarding as it was never possible to be as responsive as you'd like to requests.