I actually typically don't like characters with super large breasts, but I find her adorable..
For these sorts of questions, it's always pretty easily answerable in this way:
People like a character you don't find as attractive.
Look at the types of characters you yourself like.
If they don't line up with the characters you like, then people enjoy a type of character you don't.
If they do line up with the characters you like, then people enjoy a type of character you like.
If they line up with the type of characters you like and you don't like the character, then maybe look at the specific differences that set that character apart. You may even learn something about your self.