I figured it was only a matter of time before someone brought out a picture of a pro and said "if they don't need it then I don't either."

Nobody said that you need one.

They work. Wear one or not, it's your choice. I don't really care.

Edit: As for the full zip, obviously you don't need a full zip either. Of course you can survive without them.

In previous years, our team jerseys had 3/4 zips because Voler didn't make full hidden zippers, and our designer wanted hidden zippers because the asthetic of not showing a seam in the logos was more important to him than the comfort.

The year, the designer actually races his bike, and comfort was more important than having a hidden zipper. Full zippers are much nicer because you can unzip them all the way for better cooling. Not just a little better, but a lot, because it opens completely up. And you can also take the jersey off much easier, especially when the pockets are loaded.