Kadamon, one of the things they are referencing is when they remodeled the human female face. People logged in, and saw their character's face completely changed. Their eyes now looking different, and their cheeks thinner. It made some people upset.

Never think that someone couldn't be attached to a lower-quality model. People get attached to the way something looks, and even if it's low-poly, they can get upset when it gets changed without the ability to change it back. Imagine the new Druid Tree form. Technically it's higher-quality, but the majority of the people think it's ugly. The demand for the old tree form was so great, they put in a Glyph to use it instead.

Blizzard has said if they change the models, they will give people the option to use either the old ones, or the new ones. I simply hope they only update the original models, because the ones introduced in Burning Crusade look fine. I wouldn't want to enable newer models for everything else, and have to see the Burning Crusade models updated as well, as they are fine.