I just rewatched Ds9 over a few months. And I am currently at the end of S07E02.
Three things spring out to me that might be worth considering:
1) It was made clear in this episode that Sisko's whole life was ordained by the prophets, and Dax always felt like an important character to Sisko and resultingly the entire Alpha quadrant story. At the appearance of Ezri I became certain: Kirzon the mentor. Jadzia the friend. And Ezri the student. In all of those roles she molded and guided Sisko. Too many things happened in this episode to make it clear to me that Ezri following Sisko in wonder would lead to the penultimate conclusion of this 7 season story.
Particularly I liked the point at S07E02 43:01 Ezri says to Sisko "Benjamin, that must have been some orb experience." He looks up at her and replies "I'll tell you about it some day."
Not "... some day Old Man."
To me, that obvious absence showed a resolution that he saw her as an apprentice not the once equal and previous superior Dax of his past. I mean seriously, no good story is complete without someone in awe of you to tell it to.
2) It was made very clear in an earlier season that the Symbiotes were actually compatible with a much larger percentage of the population than the commission ever wanted to admit. This opens the door for Kirzon to be "The ready". Jadzia was clearly 'The conflicted' or 'Ready with a measure of effort and determination'. Leaving Ezri as simply the Dax who was 'Not ready'. Ideal for the roles they needed to play in guiding Sisko. And totally allowed by the shows canon writing.
3) At the end of S07E02 note the position of all the main characters in the last scene. Then look at Ezri's clearly eye contact driven look off camera in the final shot. Worf had turned around by then. It was clear her gaze was met by Julian. Brilliant foreshadowing!
Honestly. For me, at this point, Ezri is just the conclusion of truly masterful multi arc story telling. I was as sure she would turn up at the end of S07E01 as I was that Quark would volunteer to go with Worf, Julian, and O'brien on Jadzias Stovokor mission. The story was so cleverly written that nothing else made sense.
As such, at this point I love Ezri. And I will go so far as to say that Ds9 could not have been complete without her.