What makes a model official

This is just my reasoning, but it seems like the models that people call "official" are usually, as you said, he ones that someone spent many months making by hand in a 3D modeling program, then rigging, and they are usually pretty much the cream of the crop, so to speak, as far as models for that particular character goes. I think it just so happens that most, if not all, of the creators of these "official" models are Japanese because A.) MMD was made in Japan, B.) Most of the models made are of anime characters and anime originates from Japan, so it makes sense to overseas users that the Japanese would know more about the character (Don't ask why . . . That just seems to be the consensus of people I've spoken too . . .), and C.) For whatever reason, Japanese models seem to be better with technology and the programs used to make the models than us Americans . . . Not to say that this is ALWAYS so, but it just seems to be true.

Well, that's my take on it anyway. And by the way, that Chibitalia icon is ADORABLE!