Today I learned the true benefit to building reactors is reducing unemployment wherever you want.
Since this is now a bug thread: if you execute an action too fast, the animations never catch up to the actual changes to the variables. Example reproduction: Quickly place a reactor before the green energy indicator of the region can fill up during the mouse-over preview. Similar things happen with the money meter as well, repro: gain more money than you can have at one time, spend it before the meter fills up. The meter will appear higher than your actual money until something else causes the meter to change.
Not a bug: I was initially surprised that pumped storage hydropower only has an effect when you play it. This makes sense with how the game works, but with its connection to the high-capacity line mechanic I got confused. You could call the regions "currently connected" but that would unbalance the paragraph, so it's not worth it.
I've also finished the game with no high-capacity power lines. I thought that was funny. Fun challenge!