Nice piece. I'd rephrase one of your points slightly - "The act of estimating doesn’t change the actual work. It still takes the same amount of time to complete the work." - in my experience, the act of estimation elaborates the work to be done, and often creates new work as a consequence. Sometimes that's a good thing, because you find something critical you could have missed, but it also turns something simple into something more complicated. So, estimation creates work but as you say, it's a good thing overall. Just be ruthless :)