@Fuedra  
We been cross breeding since “Adam and Eve” we label things with 10 words that all mean the same thing. Care-free/Lazy/Gay in the Loony Toon area termanology/happy go lucky ect. We think and express thing’s sometimes in the wrong way or when we read something as a group of 10, all 10 have different ideas to what they read.
 
I could see Twilight in character doing it for the Science!  
I can see Fluttershy doing it to become stronger.  
Pinky Pie to be a party boy, which we all know is a thing.  
Rarity is sometimes said to be older, which is sometimes the point where people can go through with the transformation because you know they finally have a job. Reason wise I could see it because she wants to use Her self for male fashion.  
Applejack could do it to make sure the apple tree line continues [because Big Mac is totally not settling down]
 
Those….are silly reasons. I could explain the logical reason behind Rainbow and any pony but, eh only if asked.

@lynxpet  
The native voting has a lot to due with the subject matter, as well as the character the artist chose to go through the process of transitioning genders, for a lot of people believe he made his choice solely based on Rainbow Dash’s tomboyish behavior, at least from what I have heard.

I really don’t know why there is suddenly this negative voting for the comic but I enjoy it very much.