I'm expecting that raise/lower will go through some serious balancing and tweaking, because right now it's pretty overpowered
Why would you ever build a navy/transports? Just build a land bridge and be done with it (I'm guessing ocean currents and their weather and food implications are not modeled).
What I think I'd like to see is that shards augment the power of your spells, such as raise/lower land, allowing you to make a bigger impact.
So without an earth shard, maybe you can raise/lower bits of land to help your people get arable land for farming and building but you can't plow through a mountain range (well, maybe if you spent a few years doing just that). Then, with an earth shard you can raise/lower hills and eventually carve your way through a mountain range. With 3 shards (or whatever), you put modern excavating to shame. With 6 shards, you raise and lower mountains at dawn and dusk because you like the way they change the lighting to your bedroom.
That makes shards definitely important but doesn't mean you're impotent without them. I hate starting the game, looking at my spell book and realizing "Gee, so maybe some day I'll get to use some spells. If I find a shard. And the shard happens to be one I need. Guess I'll go use my sword."
[Edit] I realize this went a bit astray from the original topic
So let me say, I'd rather the game did a connectivity test for each continent to prevent getting locked away. Then let power with magic & shards allow us to warp the land to our wishes 