If you measure precisely, you will always be able to recreate the dish exactly as it was made in the past. You can communicate the measurements to another and have the dish made exactly the same way over and over and over. That's important when you are cooking for someone with a very sensitive palate, or creating dishes for those folks who expect regularity. Baking is also very much a chemical science with precise measurements of wet to dry, leavening to flour bulk, and flavorings. A slight adjustment in baking may make your time and effort only worthwhile for the hockey rink.
On the flip side, creative cooking with measurements based on emotion and spur of the moment can result in a dish that is wonderfully aromatic, sensational taste, and spot on for the moment. The upside is creative license, the ability to deal with missing, strong or weak spice flavors from the local cabinet, and the capability to showcase understanding of flavors while balancing the palate of those to be served. The need to taste frequently and adjust accordingly is both a benefit and a curse when cooking ad hoc. The dish will never really taste the same again, and failures are guaranteed as often as magnificent accomplishments.