It's in fact much more difficult than it first seems. Sure you can get up and running in a few days and even be able to create some acceptable models for testing, beyond the usual teapots and geospheres. And it's certainly a good thing to know, if just to create good testing environments for your game without needing to resort to an artist. But there's a world of difference between the programmer art generated this way and something like this or this. It takes years to master the skills needed to create really good 3D models. And that applies to characters as well as most other complex 3D models or scenes. Keep in mind that 3D art is about much more than just creating the geometry (which is already hard enough). Textures and materials are just as important.
I'd say it's good to at least know how to open a program like wings3D or blender and make a quick prototype shaped object. Also rigging in blender while challenging can be learned in a few days. It's not as difficult as it first might seem.
It's actually a major challenge to find really good 3D artists nowadays, even if significant pay is involved.