Other points
A needless luxury to one can be a necessary expense to another. There is a lot of difference between a traveler that is difficult to use (pins and slides) and one that can be eased or brought up with one hand (Harken's windward sheeting car, for example), and the advantages of the latter are many. Once you have the main trimmed the way you want it, you can ease the traveler in a puff then bring it right back to where it was and you will have exactly the same trim on the sail. When you feel the helm get heavy, you can ease the traveler and keep the rudder more fore-and-aft for less drag, then quickly adjust back. When racing in variable winds I keep one hand on the tiller and one hand on the traveler line, and use the latter at least as much as the former. In short, it gives you quicker and better control over the main plus the ability quickly to reset the main exactly how it was, as well as allowing you to keep rudder "drag" to a minimum. Once you are used to it, you won't want to go back to mainsheet only control of the main.