While the Vee is only one aspect of a given hull design, it helps to accomplish several objectives. First, it provides for a stiffer hull with less weight. Secondly, it acts integrally with other portions of the hull design to enhance tracking while level and carving when leaned. Additionally, a Vee shape functions as an integral rudder, helping keep the kayak on course regardless of how much of the hull is engaging water at any given time.
In wavy conditions, much of the hull is out of the water periodically, but what is in the water is working to help you stay on course.