Not sure if this is helpful but, for me, natural/unnecessary desires are the "sweet spot" of living as an Epicurean.
At some point a person has reasoned through what is unnatural for them and ruled those things out for themself as something to pursue. Similarly, at some point a person has (hopefully) secured their natural and necessary desires for the foreseeable future. The natural/unnecessary desires, then, are everything that's left, and these are the desires that we work with every day. Do I want to do something extravagant, just for the fun of it? This is a practical opportunity to examine my desire and evaluate how it might affect me in terms of pleasure/pain. Am I embarking on a large project? Say, perhaps, a home remodel. How can I maximize my pleasure in this instance, both in terms of the experience and the outcome. Am I deciding between two jobs? Do I want wine with dinner? Paper or plastic?
As Epicureans (or Epicurists) we don't just set up our lives and proceed on autopilot. And working with natural/unnecessary desires is one way to intentionally live day to day with the philosophy to consistently and responsibly maximize our pleasure.