Yeah I will need to address the crystal issue - they need to be scarce enough that they need the player to adventure out and be prepped and ready, but not so scarce it's annoying and unfair. Kinda like Subnautica with rarer materials that force you into the depths... that's the vibe I'm going for with it, in a roundabout way.
The world should feel big enough that getting from one major city to the next or one major region to the next feels like a triumph. The portals should make it easier to navigate across the world once you unlock them though - so it's not just busy work, it should feel rewarding and special. At least, i hope so!