Is it cheesy? We can certainly make underground bunkers IRL, which is more or less the same idea. A giant pile of rocks, which is what raised terrain represents, seems like a fine way to keep out the rabble (our enemy have mostly animal level intellect if that): its cheap, its easy to repair, and it works.

I suspect that troll picks will actually happen (at release, the enemy may have a way to get through them). Or not. The game is 80% about building beautiful/cool/funny/etc things. If all that stuff gets broken every hour or so, its like trying to have a snowman around a bunch of kids -- its gonna get trashed when you turn your back. There really must be some way to protect the builds, or the game becomes totally useless to a lot of players.