Out of curiosity, what's with the general dislike for JCM?

I'm no expert with how Poser figures work, but I really like the idea of JCM.  Being able to have morphs adjust depending on the joint rotation is damn powerful stuff, and I can't imagine anything that couldn't be achieved by using it.  Poser even allows us to sequence the actuation of the morphs using a timeline for each joint, and further still, even has an adjustable actuation curve!  I mean wow, that's powerful stuff!

So personally, I don't get the fascination with weight mapping and the general shunning of JCM.  If I were a designer of a program using this stuff and I had the choice, I'd go with JCM every time; the power we have for shaping and controlling stuff using that technology is limitless!