I thought a turn-based game would be simpler to make, too. But in implementing this I see more clearly how much I've actually been struggling with this. Refactoring to the new approach is simplifying everything. Deleting a lot of code this weekend. Feels good.
The original goal for this game was to be a multiplayer game you didn't have to spend much time playing. This led me to a turn-based approach, where turns would happen at some increment (8 hours?) and users could queue at least a day's worth of turns ahead of time.
My solution? An energy system. You have a pool of energy that replenishes on intervals (8 hours or so?). You spend that energy and receive feedback immediately. Probably the most common system used in browser games? I think I have a better understanding of why now.