There's an old space civ game called StarKnights that used a system like this. You gained movement each x period of time (configurable when making the map). It worked fairly well, until players found each other. If someone got the chance to go before you, they could do serious damage.
Another issue was not being able to play the game if you ran out of accumulated time (you weren't kicked out, you just couldn't do anything of real significance).
Anyways, I bring this up because I do kinda like the idea of having an accumulated time system option. I think it could work for larger maps. With some brainstorming, I bet we could make it pretty balanced. Maybe have certain rules that prevent players losing too much while away, and rules to kick players if they don't log on in x number of days (so the game doesn't get stuck by sore losers or people who lost interest). Maybe have a cap on the number of accumulated turns.
So, there are a lot of knobs that you can turn when it comes to this idea. I'm not sure how important it is to try to make this work, given the limitations of time on Stardock's part...maybe if they run out of ideas on what to tweak or add to the game lol.