A lot of modelers who were around when they made the character models we have now, are no longer around. They did the models they wanted to do - with a bit of balance in mind: a human, elf, dwarf, and something more unusual. But as we said already, we can't predict nor estimate when the other models will be finished. We only have two 3D modelers on the team right now, and they are working on other tasks.
We will have several wipes before new models are introduced, and I think it would be a good idea to time releasing the future models when everyone will have to recreate their characters anyway.