Maybe we should revisit that - I've never found it particularly enriching that all instances of a particular type of object have a fixed amount of PP that can be allocated to them per turn. Instead, the amount of PP that can be spent at a particular location could be determined by other factors.
Consider the following:
Perhaps each producible item has a "Production Group" associated with it. Each planet would have a PP limit for each production group, which would be the maximum PP that can be spent on items belonging to that production group at that location. Thus, Constructed Shipyards would contribute to the "Constructed Ship" production group PP limit, or whatever, whereas an Organic Shipyard would contribute to the "Organic Ship" production group PP limit. Rather than having hard location conditions for particular hull types, it could just be vastly impractical to build a particularly expensive hull without an advanced shipyard of the appropriate type.
In theory, i'm not opposed to a location based PP limit instead of a per part PP limit. Though on the other hand, the advantages don't leap out at me.
But if it were location based, "Production Groups" seem an overly complicated way of doing it. I'd much rather see a single
limit value per location, based on techs, buildings, specials, species, population and/or infrastructure, etc.
Also in general, for the sort of game we're making, i don't think making something "vastly impractical" instead of impossible is likely to improve the game. The danger we have is burying the player too many build/research option. Adding a bunch of almost-always-bad choices to his build options, just gives him more things to ignore.