I have to agree. I never really liked old west stuff or pirates, per se, but the Western themed pieces, especially, in PC1 were also so useful for building the more Victorian-esque buildings that I prefer, and would've also been great for making, like, a New England fishing village themed area in this new game.
I don't think I ever used many of the Sci-fi themed pieces in PC1 either, but I'd imagine a lot of people will miss that if it's not in the initial release.
Anyway, I hope they'll give us back the old themes, if not in the initial release, then in a DLC later (hopefully very soon). I mean, it seems like all the old scenery pieces would be relatively easy to port over since they're already modeled -- just a bit of texture tweaking, adding the ability to scale, etc.