So I was discussing the other day with another player that we both wished that deconstructing a building would yield some return of invested resources, essentially reclaiming a partial cost of the resources used to build/upgrade the structure. We both felt that this would help players that don't pay to play, whether they don't want to donate or that they can't afford to.
Specifics: a percentage of the resources used to build would be "reclaimed" when a structure is deconstructed. If an item is used to destroy instantly, there would be no recovery, (item too powerful, turned the structure to dust). This rewards the patient deconstruction times. The intent is to gain something from locked buildings toward later ages. An alternate way to implement this would be to make it a research based attribute. It would be a good companion to Chariot at the Logic juncture of the research path and Reclaimer or Forager, or something along those lines.