Yes, I think the scarcity of some resources opens up for more interesting choices and diplomacy options.
Also, getting all resources available early in the game would hurt replayability. Each new game should be different imo.
Scarcity only helps in Diplomacy if the AI can actually, you know, play it. Sadly, right now there is none.
Right now I dread the idea of playing in anything bigger than medium because I would surely end all my games like: "I have stuff, my opponents have stuff and in the rest of the map, we will be lucky if there are more things aside from Shards (which will be also few by themselves)". Because it will only mean "I have to wage war against my opponents because there is no other resources but theirs and I'm forced to cross all the damn map to wage war upon them, crossing totally empty map... except for the bandits and spiders that spice up the landscape.". I already have that in medium and for that, let my enemies start near me and lets have war from turn 1. ¬.¬
To have reasons to explore and expand is nice. Specially if it means we can lessen our "Lets rush the enemy because there is nothing else to do in the map. Except kill bandits. And spiders. Add bears and darklings too.".
I agree with your last paragraph. It's the frequency of resources on normal which worries me. They are not suppose to be so scarce in that setting. That or the description should be changed.
