Is it possible that the Production builds might have just the relevant Systems from a given pack installed while cross pack compatibility is being tested? I mean, if they're working on adding something like Zodiacs or School Breaks into the game, they don't need the full Seasons pack installed, just the calendar to make sure that they appear there appropriately. (Moon Phases I'd assume they'd also want the weather to see how the moon's changes worked with different cloud covers.)
Personally, I'm in the "fine by me" category when it comes to moving systems from the expansions to the base game when needed for a new pack. Especially since their other options are to include the system with the new pack, which will result in people complaining about paying for the same thing twice, or DLC for DLC which will go over like a lead balloon. They can't win. And at least with making things base game, they can avoid accusations of cash grab.
But it also strikes me that we may be making a big deal out of nothing if it's just a quirk of the production build.
