I don't mind the concept and stuff, but why does a humanized fluttershy have breasts as big, if not bigger, than her head? I don't get why everyone thinks because she's shy that she has to be gifted in the chest area :/
Because Doxy likes the boobs, no other reason whatsoever. Same way he thinks that Rarity's are just as big, while Twilight's are smaller, Applejack has medium-large, Pinkie is bouncy but more of an ass girl, and Dash is so slim she could pass for a boy if she wore a hoody
It's a good question, but one many have asked before, in this case it's as simple as that; the artist has it in him to enjoy big boobs and thinks giving them to Fluttershy is pretty hot.