Updating existing character models isn't something we've been "waffling on." It's something we'd love to do, but the fact is the art team has finite resources. Updating the current playable race models to be more in-line with worgen and goblins requires much more than just increasing the poly count. There are more bone structures on the frames of newer models which allow for more animation options. In order to update older models, the wire frames have to change, which means a large number of existing animations and customizations/hairstyles would have to change.

It's much more of a massive overhaul than many players are anticipating. That isn't to say we don't want to do it, but it's difficult to justify delaying the creation of new art, models, and animations indefinitely to revamp old ones. And we have to make sure to do it in a way that doesn't give some players a feeling of detachment from the look they've had for almost seven years.