At the very least, they cost city production time (they use the nearest city's production queue).  With all the things that go into it now, I would say that that's significant.  Not sure if there is any other cost.

I understand that they've made all the monsters librarians, and converted the outposts into post offices.  Too bad.

...Do you really think a company that has been creating successful strategy games for over a decade would decide to remove a key element in this style of game, this late in its development...?   If anything, I'd bet they're trying to increase the level of unease and instability for the player's units once they wander around this dangerous world.