Why would I want to be able sketch when I have this computer, with all design software imaginable and more fonts than I could possibly know what do with?
Sketching as a Communication tool
It is properly the best communication tool out there, so as a project manager, if you can sketch and illustrate you perspective, you ideas, time schedule, diagram etc. then you will be able to give the audience this same overview we always are searching for.
You can see more of my skills on this link.