You are assuming that the pre-rendered model is better than the rendered one. You indeed have more freedom with poligons, but who draws the better models ?
The extra freedom with poly's is exactly why its easier. Take hands for example. With prerendered, you can shape them far better then when you would do for a 3d game model.
With the latter people go to great lengths to make the textures extra detailed to make the model look better. This is less of a necessity with pre rendered models, because the extra polys already take care of (all) the details.

I understand what you are trying to say though. For the past 3 years I've been doing 3D graphics, and although I am getting better at it, I still find it quite difficult at times. It's just that I think it is a misunderstanding to think that (high res) pre rendered graphics are harder than low-res 3d models. (When you want to have them look just as good or nearly as good as pre rendered)

While a simple low poly model can still look nice in 3d, it would probably be ugly in 2d.
Actually a low poly model will always look better in 2d than it would in 3d. You have after all the benefits of shading, lighting and antialiasing.