Smart and insightful of her to figure out that she doesn't know it all, or has all of the answers.

As for Twilight, there always comes a time when the teacher declares that they've finished their task. It's time for the student to transcend the teacher.

Personally, I feel Magical Mystery Cure could've worked.... if they'd devoted the entire episode to it or even made it a two part episode rather than having to shoehorn in the whole alicorn Twiilight bit. And it might've still worked the way it was presented if the whole alicorn business wasn't already spoiled in... I think a colouring book, a year earlier.

Magical Mystery Cure was flawed, heavily HEAVILY flawed from a narrative standpoint. A situation like this should have been built up largely in the foreground of the story... actually, the events of Canterlot Wedding should have been built up in the foreground too: a large-scale battle in the heart of Canterlot would have been extremely awesome to witness.

How to build up Canterlot Wedding 101:

-Throw in some more Luna!
-Casually namedrop or mention Shining Armor as either "Officer Armor" or any variation of ranking as the show continues onwards, but DON'T directly mention him being Twilight's older brother until the penultimate episode.
(E.G. at the Gala, Rarity is approached by a nondescript Shining Armor in a Solar Guard uniform and the two of them chat it up for a while. During Discords crazy antics in the following episode, show the same Shining Armor (here referred as "Officer Armor" and a unit of others try and evacuate a Discorded portion of Canterlot and have Shining manifest a magic shield to protect a family of Earth Pony visitors. Then in Sweet and Elite, have Rarity again meet Shining Armor again ("Oh, Officer Armor. I didn't expect to see you here." "It's actually Sergeant now, I earned my rank during Discords' attempted affliction of Canterlot a few weeks back." Also in this version of the episode, Rarity has journeyed to Canterlot with Sweetie Belle instead of Opalescence, which I felt SHOULD have happened, that way people wouldn't just see Rarity as a cat lady too much). This sort of meeting with "Armor" would be a Side-A, while moments involving Twilight would be a Side-B where she would casually mention her brotherin passing, in episodes where Spike is in focus he would namedrop "Uncle Shine", and in scenes with Twilight Velvet she would briefly say that her children are off doing important work for the good of Equestria. This would all come to a-head in the epitme episode where things are radically changed: instead of a wedding that kicks off the plot, in this instance we have Rarity, Twilight, and Spike going by train up to Canterlot in attendance to a celebration at the bequest of the new Captain of the Solar Guard, who asked for their attendance, Twilight and Spike go off to see their family to celebrate the birthday of Twilights brother Shining, while Rarity heads off to meet with the soon-to-be "Captain Armor". Captain Armor is then summoned to the residenceof House Light (the name of the Noble House that Twilights family is comprised of), Rarity herself is worried that her best friend might be in danger as they rush off to the residence as the two of them burst through the door as everypony inside yells "SURPRISE!" and leaps out from behind as dual banners drop down: one saying "Happy Birthday Shining" and the other saying "Congratulations, Captain Armor", and this is when Twilight rushess out and hugs Captain Armor on the neck and telling him "Happy Birthday, Shining Armor!" And Rarity is completely shocked and surprised at this revelation of character just like everyone else that was watching this scene.

And this was waaaaay before Twilight became an alicorn.