It's simple: If one of the things breaks, do you want to buy a new Joy-Con for almost 40, or have the option of replacing the part individually for 10 CHF? It's actually always good if each individual component is available separately, because individual components can also suffer damage independently of each other. It's always a question of: When in doubt, give the customer the benefit of the doubt - if they are sold individually, no one has to buy them, if they are only sold as a set, customers are always forced to buy the whole set, even if they only have to replace one component.