There's been mods that explore resource scarcity, Hyperion was more along those lines. Default EFS and Nova ultimately all have a form of resource scarcity in gems which restricts you on how often you can build jump capable ships. The expensive engineers are a theory I like too, but I just don't think it would translate well into how the game flows, primarily because the galaxy is not balanced and it would slow down an already very slow game that virtually no one ever finishes. I too would have liked to see industrial cities cost more and be more important. Perhaps if there had been two kinds of engineers, one that builds primitive, low tech cities like mines, farms and wells, and 20x as expensive advanced engineers used to build forts, starports, production industry and so on. That way you could build up the resource infrastructure at the same pace, but a fort, or starport, or cyclotron would all become immeasurably more important than they already are.
Suppose you were betrayed early in the game and lost most of your starting transports, with greater engineer costs of that magnitude, if there wasn't some kind of compensation of resources, it could literally be 75 turns before you create transports again. I think the ability to create overpowering forces that can overwhelm defenses is one of the only ways its possible to win at all.
A forum game is interesting, considering fading suns itself was a role playing game in the vain of D&D. But I'm not sure I would be very interested in it, if only because I prefer graphical representations when a game is of this magnitude.