the stockpile has two uses
- stockpiling unused PP
- and more important, providing a means to build outside of supply groups .
As the content moved to providing most of the stockpile only if setting the focus to stockpile, stockpiling unused PP does not make much sense (as you could probably provide more production if you put the focus on industry).
So what if we get rid of the stockpiling unused PP feature and just keep the means to build outside of supply groups?
In that case instead of the stockpile extraction limit we would have a location independent (imperial) industry meter instead, directly giving the means to build. That would simplify the concept and the UI a lot.
Note: stockpiling can make sense for the non-focus related stockpile-extraction. but it is either very small or the species have to be good/great at it. and the intention there was to make distributed production feasable.
Side note: unused PP would go to waste as they were before. also unused imperial PP would go to waste.