I have a feeling that this lesson is leading up to something like "I will soon be about to have been having been finished"...
Well, "makes more sense" only if you disregard that perfect tenses in English are formed with "have" but in Esperanto with "esti".
If you took a different word such as "Baldaŭ ŝi estos (fin)skribinta la libron", you couldn't say "Soon she will be written the book" but would have to say "Soon she will have written (finished writing) the book".
It is much simpler, but it's less precise. In the above examples, you could get away with using the simple tenses, but there are times when it's very useful. Compare the different meanings of these sentences.
Kiam vi alvenos, mi kuiros la vespermanĝon. When you arrive, I will cook dinner. (Presumably arrival, then cooking)
Kiam vi alvenos, mi estos kuirinta la vespermanĝon. When you arrive, I will have cooked dinner. (cooking, then arrival)
Kiam vi alvenos, mi estos kuiranta la vespermanĝon. When you arrive, I will be cooking dinner. (arrival during cooking)
Kiam vi alvenos, mi estos kuironta la vespermanĝon. When you arrive, I will be about to cook dinner. (Explicitly arrival then, afterwards, cooking.)
(Optionally, you can remove estos from the sentence and attach the future tense verbal ending to the participles, giving kuirintos, kuirantos and kuirontos but apparently that's fairly uncommon.)
Estas bonaj klarigo kaj diagramo en Vikipedio pri tiu subjekto: https://en.m.wikipedia.org/wiki/Esperanto_grammar#Participles