One of the biggest furphies of story structure is the mandate that the starting point and driving motivation are a character's desires, sometimes distinguished between wants and needs. But when you look at the examples the pundits give, very often the starting point for these so-called wants and needs is simply maintenance of the status quo. The hero's true motivation and drive are catalyzed from outside (call to action), and initial tension (refusing the call) is not a matter of active desire but passive resistance and the comfort of the known, and in the end the matter is taken out of the hero's hands by events (catapult into the new world).
Indeed this lack of motivation is an intrinsic part of the hero's journey mythos: farmboy must take on the role of a knight to rescue the princess. Whether Theseus or Skywalker, the drive is not a matter of the peasant's desire (which included neither riding into danger nor romancing princesses), but arises from character (the contradictions between doing what is right and playing it safe).
Some stories look different.
In Dragonflight, Lessa of Pern has a burning desire for revenge against the usurper Fax and the restoration of Ruatha. But this is a function of a particular choice of in medias res - starting in the middle, when she is 20ish, as dragons approach and she is about to be pushed into a new and different future. At this point she does seem to be a peasant, a kitchen drudge, but the true inciting incident happened when she was around 11 and effectively a princess, and still true heir of Ruatha. When she was 10, she was quite happy with the status quo, but having that removed installs a drive for return to that original status. So she is forced into a peasant role now but was happy before, and her drive is restoration.
In Dragonsinger, we actually see Menolly's gift of music nurtured until her mentor passes away (happy with the status quo), and then stifled and repressed by the family with the final straw of debilitating injury. So we have a catastrophic effect (whether the natural enemy Death or the inhuman enemy Fax or the injurious intervention of) that disrupts normality rather than unrequited desire as the starting point. But after the catastrophe there is a burning desire for music.
So it is not that the plot emerges from the burning desire as the pundits claim (although this is how it might appear in a shortened in medias res form). Rather this desire or need is created and fanned by an inciting igniting event and then the way to reclaim it is opened by an exciting exiting event. Note that the inciting event is inward, directed at and impacting our heroine directly and initiating the drama, while the exciting event heralds exiting the old world she is trapped in, directed outward to a new world with new discoveries.
The desire is created by the plot, or latent and released or excited by the event that catapults our protagonist into the new world.
In a saga, we are always in medias res. There is a heritage that lies before, and many heroic cycles that lie in the future. Anne McCaffrey built both backwards and forwards from her opening shot. Neither the series nor the initial novella were plotted as such from the start. Indeed the novella originated in a short story that garnered a Hugo, and then a second that won a Nebula award. It was the fans that forced the saga to continue. And the other stories, like Menolly's, have more traditional character arcs that start at the beginning of their lives, and show them being forced out of their comfort zone - the plot revolving not around satisfaction of wants and needs but going beyond all expectation, and recognizing a hidden depth or releasing a trapped or nascent gift.
The Dragonriders of Pern also illustrates another truth about genre: exciting things happen when you spurn the genre tropes and subvert the expectations. McCaffrey imported the dragon trope from fantasy but gave it solid scifi worldbuilding: Pern was a colonized planet without the means to maintain a high tech society, and it had a problem: the red planet and the thread it brought. The founders came up with a clever long-term solution involving the genetic engineering of the dragons and the social engineering of the harpers.
