Exactly which subordinates do you expect to be easier to reach, after building this? It's a north-south passage through the boundary hills.
Sorry, I probably should have said it lets our subordinates reach
each other, with reinforcements, trade, and messages. I do think it probably also lets us access the north from the core more easily, but I can't prove that and so won't argue it.
What it indisputably provides is a blueprint / proving grounds for roads through rough terrain.
And you left out the value of a Cultural Hero to keeping our subordinates loyal. Stories that make people feel like they're part of a great nation make them slower to want to go their own way.
The problem with Heroes is that they all die.
I have no doubt that a Cultural Hero would raise loyalty and keep our subordinates perfectly in line. But once they died
, unless they set up a system to continue past their death, we'd be back at square one. Sure, we'd have higher Loyalty to work with, maybe even a legacy if we got very lucky, but the problem inherent to the system would remain. And once Loyalty drops, as it always does, we'd be back at square one eventually.
If people think we can handle the cost of the Cultural Hero, and are willing to adjust next turns' plans and our policies accordingly then I'm willing to do it. As it stands, though, we are reliant on Culture overflow to prop up Tech. I am reluctant to burn
both Culture and Mysticism while spending a lot of Tech continuously, which is the situation we're in right now.