I think some people are confused about how to best utilize the Samurai's new ability. For your core cities, absolutely build/buy workboats ASAP for the added benefits. I have a game now as Japan where I went Tradition, got my core 4, built/bought workboats, then for my newer cities, used my Samurai to build the workboats. It allowed me to focus on other buildings in these new cities, which is very helpful.
This is also great for puppets since they will never produce a workboat, nor can you buy one there. It's not supposed to be the main way you hook up your resources though. The argument that you have to go out of your way for Samurai so you can make workboats it's just silly. Again, it's mostly for secondary cities.