I think they should have added some more terraforming options to compensate though. I think there are 5 tiles max you can improve now with buildings? 2-3 more tiles would be fine and great for builders. It's easy enough to mod, so not a big deal really. 

It's pretty easy to mod back in:

Just follow the directions given in Reply #3 of this thread: https://forums.galciv3.com/471809/get;3590824

This. The Ultra Terraformer was way too powerful but they should have added a few additional terraforming techs allowing you to improve a few more tiles.

Or, actually, why not keep the "eventually terraform everything" idea but combine it with the existing restriction mechanic of having to research a new terraforming tech each time before you can add a new tile? This could be accomplished by having a "loop" in the tech tree that gives you "Ultra Terraformer 1", "Ultra Terraformer 2" etc. allowing you to always terraform one additional tile each time you research a better version of it.

As a bonus it would also solve the "nothing to research" bug as you'd always have at least this to research.