@Background Pony  
@Takuto_Shindou  
Rarity was originally meant to have an entire scene with Princess Luna and Twilight wherein she makes a dress for Luna to make her appear less ominous to everyone, but the result was naturally too bright for Luna. The scene was cut for time and pacing.
 
It makes sense that her earlier apperance would be replaced, since Carrot Top has been associated with Derpy for a while (making it an early “brony shoutout”). Don’t worry; it was not pandering but merely an adjustment for pacing. By including Rarity but not giving her a speaking role, it would appear awkward since you would otherwise expect that scene to foreshadow her having later involvement.

@Takuto_Shindou
 
Other offenders may have been Pipsqueak, who only appeared on that episode and whose role could have been given to any other pony without introduction, and Fluttershy, whose scene was pretty much useless (Twilight got Luna to speak quietly, not her)

Bu… Bu… But, I thought Rarity WAS A Background Pony in S3?

@MagnificentTrixie  
As far as i’ve seen from the show, they are arrogant, mean and selfish, i don’t understand why people insist they are nice on the fandom.

Learn to speak English.

@Takuto_Shindou
 
Oh, don’t be like that. They’re adorable in their own special way.

@Background Pony  
And that’s when my hate for bg ponies began

Sh was meant to have a cameo but they replaced her with Golden Harvest

The writers didn’t have enough time to fit her in.  
Even though they had time to fit in everypony else.

Rarity is the underappreciated doormat of Ponyville. True story.