Release older buildings for newer players!
Well, many of the items were limited time or tied to episodes, so it wouldn't make sense to release them again. They have released some old items here and there so you never know though.
Forum Discussion
I say release all the exclusive buildings to new players. Making the game that much more enjoyable for newer players guarantees they'll continue playing. Any long-time players who throw a fit over newer players getting to experience the full game are gross, bitter farts and need to calm the hell down.
