Just fyi, the OP's claims about the science are incorrect due to more recent research into dopamine and how it seems to work (and researchers still do not know all the details, which is why research is iterative and helical, not final).
You can read an excellent post at Gamasutra by a researcher who wrote his post from an academic viewpoint, including citing academic sources. The author covers the history and how it relates to game design, as well as the newer research that refutes prior conclusions.
http://www.gamasutra.com/blogs/BenLewisEvans/20130827/198975/Dopamine_and_games__Liking_learning_or_wanting_to_play.php
In short, current understanding from research is that dopamine seems to trigger a
desire to receive rewards. In the case of Civ IV and V, if someone doesn't like Civ V, it isn't because the design does not offer a regular stream of rewards, but rather that the person in question simply doesn't feel a desire to strive for rewards. The same is true for Civ IV: any individual may not be inspired to strive for rewards in Civ IV for various reasons related to the game's design (including the regular stream of small rewards or the micromanaging needed for the game, as either of these elements may suppress the triggering of dopamine in various people and thus undermine their interest in the game).
Such research is extremely relevant for all activities, including game design, especially when current game design viewpoints are based on outdated conclusions that more recent research has modified.