Building extensions in Photoshop often requires to make operations as fast as possible.
While javascript API already offers some of the functionality, all of the functionality required is already available by running actions in batchPlay.

It would be great to get a javascript library with all functionality working as a wrapper on top of batchPlay, while still having access to low-level predefined batchPlay actions.

This would allow developers that don't need advanced functionality leverage power of batchPlay by using js wrapper directly and developers that do need advanced and fast operations chained together use pre-defined batchPlay actions directly and chan them in the necessary order without using javascript library methods directly.

As a more concrete example.
PS UXP JS library could expose builder methods that would allow to build ActionDescriptors for batchPlay like Layer.ActionDescriptors.rename(parameters) could return a descriptor that would rename a layer based on some parameters.
Or there could be Channels.ActionDescriptors.invert() or maybe even Calculations.ActionDescriptors.calculate(properties) or even prepared descriptors for Adjustment Layers and operations on them.

Then javascript UXP library could be using same low-level descriptors to have a more high-level set of methods like
renameLayer() could be internally using Layer.ActionDescriptors.rename(). And while low-lever descriptors are exposed, advanced users would be able to leverage them too directly.