Kites are more complicated than spinnakers which are already “fishing junk out of the water with extra steps” complicated. It is promising for solar electric boats, both as backup power, and voyage power boost, but even if they are promised as autopiloted flight, there needs to be a lot of experience in how to use them and when to bring them down ahead of weather, and lulls are big problems. There are commercial ship models, but I’m unaware of success stories with customer satisfaction.