Well, for things like hips and arms, one sometimes has to do complicated things to get a figure to look nice in every conceivable pose. So for example, I would make separate JCMs for the x- and z-rotation of the thigh, then I would apply both rotations at once, fix the resulting shape and add half the difference to each of the existing JCMs. Another option I've seen discussed is to slave a new JCM to a product of the channels. It's pretty tedious to set this kind of thing up by hand, and it would be nice to save it independently of the CR2 and load it back in later (also for example, to make JCMs for a variant of the figure or an item of clothing that would use the same ERC settings).

You're right, one cannot create morph channels via a pose file (at least that's the conventional wisdom, and I haven't seen evidence to the contrary). I forgot about that. So I guess that would still require one to paste some channels into a CR2. Still, having all the deltas and the ERC setup condensed in one pose file would be very useful.

I'm not saying this kind of functionality would be necessary right away, as it seems pretty advanced and maybe not many people would be interested in it. I'd be quite happy to set up my ERC by hand and "just" have your program take care of the morphs. But obviously, the easier it gets to create good JCMs, the more ambitious people will become. So maybe this could be something to think about for future versions.

-- I'm not mad at you, just Westphalian.