Of course if your using a 'planer' your by default having the A.I. think ahead. GOAP is exactly that and if set up correctly can be thinking multiple turns ahead. You just set up your goals accordingly. The end goal being the winner and several goals below that must be met to reach the end goal, with the A.I. choosing based on it's own state and what it knows about the enemy. Or perhaps the human player attacks so the 'Goal' changes to 'defend' with sub goals (how many units to send, etc)
This happened all the rime in F.E.A.R. The game didn't win awards because the rest of game was all that great but because the A.I. could think. It did plan. It called for help. It worked with other A.I. to set up flanking, flushing out and so on.
Diety Empires is another title that uses GOAP rather well...and again an Indy dev. That game absolutely has a planer as i've seen it ferry troops to an island and later pick them up once the island was explored..FSMs don't do that. And in your typical Civ game that unit would have wandered that same island the rest of the game.
Dev houses really are penny wise pound foolish. They could spend a couple years on an A.I. that is modular and then be done with it. Using it in every title going forward and gaining a reputation on that A.I.
