Watch out for the Big Bad Draconiguus!

@Liggliluff  

 
For fictional characters, appearance often does get chosen to reflect personality. (Or, in cases such as Starlight Glimmer, to suggest that the character is something other than what they’ll later be revealed as.)
 
That said, I think the build that best conveys Fluttershy’s personality would probably be modestly endowed, short, you know, the kind of person who’d generally be able from one end of a reasonably-crowded area to the other without really being noticed unless someone there knows her personally.

@RektPony, @Liggliluff  
…and following a “stereotype” (or whatever it’s called in this case).

@RektPony  
Yes … just because it’s something horny game designers do – doesn’t make it a fact.  
People commenting stuff that “Fluttershy is so motherly, so that’s why”…  
No, it’s because the artist is horny or something…

Shy girls with big breasts was always a meme made by horny japanese ecchi game designers. For them to have big breasts they either need fat or plastic surgery. Which mean that it would be Rarity or Pinkie who gets bigger breasts. Fluttershy doesn’t eat a lot and she doesn’t care about her appeal toward stallions.

@untraceablelarry  
Just for the same reasons that she would have big breasts…
 
Personality doesn’t change breasts size.
 
And I know of a very shy and quiet girl myself, and she has very small breasts.

@untraceablelarry  
Personal taste. Opinion. Fetish.
 
There is no right answer. Move on.

@Background Pony #0196  
On what basis do you conclude that? How would anyone have any idea, outside of what we see in Equestria Girls maybe?

@Liggliluff  
Fluttershy would probably have small breats as a human imho

Are these breasts small enough to be rewarded the flattershy tag?  
We need to tag these rare cases.