Surface combat is not rewarding when it becomes the default way to complete every encounter. It is fine if there are certain encounters where surfaces could come into play, but as the game plays right now it is nearly EVERY encounter.
Had a thought about this. What if placing and removing barrels from an area worked like damaging the war drums? Someone would come and investigate, if too many were moved then they would know something was up and attack. If the player carried barrels to another area and dropped them near npcs they would then move away and maybe question the player like vendors do if you steal from them. Or just make them weigh a lot more so they can only be moved not picked up.