This is another case of playing with words and forgetting the purpose or the history behind the invention of the words per se. Yes, words were invented by Human beings to aid communication.
Call it planning, call it guess or call it by any other name it is a benchmark or a landmark in a specific direction that you would like to move ahead.It can be a personal plan a corporate plan or for anything in between.
The point remains that having a guided journey is better than drifting and so here is my take on your thought.
I endorse and agree with you that we should take light and not get obsessed about planning.
I disagree on calling it just Guess work and not give it any credit or importance as you make it out to be.
Would love to have your insight and keep up this thought churning on meidum for people to get more angles to every concept.