"I mean, it's just math, right? Why can't it resize bvh data to the skeleton in Poser? A clean import would be an enormous improvement for me, since I spend a lot of time trying to fix foot-skating."

Hi Tim Looking forward to your next production.
Your work flow is quite similar to mine except that I dont have access to a Capture system and I use DAZ Studio's aniMate+  nonlinear motion system
to seamlessly mix various bits of Mocap to create
new motions and Export them from DS as animated pose files(PZ3).

Overall I cant complain about posers ability to import mocap or retarget motion to other rigs
because compared to C4D, poser and even DAZ Studio
Does an excellent job overall.

My number one biggest Complaint about poser animation tools is the fact that if I use IK at any point for feet pinning in an animation but later turn it off
so my figure can leap or kick it ruins any animation Data for the legs& hips completely.

its a shame the Code behind new animated constraint system in poser pro could not have been somehow applied to foot pinning with its strength being an animatable parameter.

We already know such a thing is possible with python
because of the way the strength of the ragdoll& collision
Dynamics can be animated with Paul's Excellent poser physics plugin.

"
**I'd just like a rig once-use anywhere solution.  Carrara doesn't export to Poser, Poser doesn't export to iClone, etc.  Is it Smith-Micro's responsibility to prevent someone from using content improperly? **
"

Hi the biggest hurdle unfortunately is the way
we "Dress" our poser figures.
right now ,other than Daz Studio, the Interposer pro plugin, that Tim and I use, for Maxon Cinema4D is the ONLY third party program that Directly supports posers "native" Conforming clothing .
OK vue sort of does but the C4D plugin allows me to change/unconform/reconform clothing inside C4D by loading it from any  runtime just as we do within poser itself

"Or as developers of the program shouldn't they try to make it as useful as possible to the most people? "

Well Ultimately thats a decision for Smith micro to make
but it Compatibility with other programs& game engines would be more easily Achieved
with Standard single mesh Figures like the Custom Spartan Characters in the red vs Blue Clip
not the modern day poser figures with multiple
conformers.

Cheers

My website

YouTube Channel