I would also hope that construction will reduce the amount of terraforming, but I still suspect that tribes may look to build a 15 metre high terrace, with a 15 metre deep trench around it and then put their buildings on top.
A defensive barricade will be more effective on a terraformed ridge and I suspect that is what we'll see.
People will raise and lower the land just becuase they can and it's going to make the place look terrible. Terraforming should not be an easy task.
Levelling is fine, but the building-like terraces that result from terraforming are too grand. I would like to see the height of any terraformed land restricted to about half a meter either side of the original height unless machinery is built to move earth.
One thing I have already learnt is that some Tribes will terraform as much as possible in this game in order to advertise (show off) their tribes and the resulting landscape will be a total mess unless the activity is curtailed.