Besides being functional, a pose should also be appealing, it should look good. Right? But... is beauty only in the pose, or is it also in the model?
For instance, if you are truly ugly (it can happen), you look in the mirror and from no matter what angle or pose... you're going to be... ugly. If you're a gorgeous babe, you look in the mirror and in almost any angle and pose you're going to be gorgeous... Pretty simple. But why don't animators care much about this, I wonder?
If you animate an ugly model, no matter what you do, your animation is going to look bad. It could move naturally and have personality, all that jazz, but the poses will still lack that graphical appeal that makes a drawing a pleasure to look at. It's easy and only natural to amazed by beautiful imagery, and it's something animation also needs, among other things. An ugly model can't possibly be posed to look beautiful.
Yeah, on the other hand, you could mess up a great looking model too, if you insist...
Anyway, take the (in)famous Generi rig for example - no offense but... the guy looks monstrous and awkward... (I mean, I apologize to the creators, but I really want to point out some things here)
(Yuck! Stop smiling..... it hurts.....)
There must be hundreds, if not thousands of animated shots done with Generi, and they all look unappealing. Is it because the animators have never managed to reach that level of... ammm... I don't think it's because the animators using Generi are unexperienced. Some of them actually are talented and do have experience. OK, maybe he can be funny, and even look cute to some, and maybe some people are, by now, so used to his design... Generi definitely has a place in the history of computer animation. But not even accidentally could you create a trully appealing pose with a truly unappealing model like this. I'd simply like to see anyone - the best Disney animator - try to create ONE appealing pose out of Generi (maybe if you hide his face...?).
Oh, and there's more, it's not only Generi, there's a whole bunch of free rigs out there that use unappealing models. Appeal is a matter of design, and it's damn hard to create a 3D puppet that looks great, it's just hard.