Animated joint centers are pretty easy to implement.

In Studio. Lol.

You load a TriAx rigged figure. Load a new full body morph you made. Click a button and the joint centers auto-snap to their new centers to match the shape and proportions of the morph you added.

In Poser, well...ColorCurvator made a script to add Kids4 as an FBM to M4. This script uses animated joint centers to work, and also works with other figures.

But the figure you "add" has to be already rigged with the joint centers in their correct (new) places.

If you need animated join centers for a custom morph fresh out of ZB that has shorter or longer arms or legs or a shorter or longer torso or wider shoulders etc, then every single joint center will need to be adjusted using its y-,x,- and z-offset dials and these adjustments need to be individually ERC linked with the dependency editor to the new body morph.

Very, very tedious, especially for the hands. Oh, wait, native Poser figures also have a gazillion bones in their toes, making the procedure just as tedious for the legs.

If SM wants their figures to be popular, they need to add such an "auto-snap" tool. People can make five completely new and original morphs for Genesis a day, because it takes only 10 minutes to properly rig them.

In Poser, just properly making an arm longer can easily take half a day or more.

That's why I usually use scaling for shorter/longer arms even though animated joint centers would be the more "cleaner" solution.

:-P

Improving joint movement with animated joint centers works the same. You set a new center point for the end rotation of the limb with the offset dials and then link that adjustement to the joint rotation dial of the limb you edited.