Bottom Line: Armor Stands are Definitely Doable. Armor Stands would be less resource consuming that many of the placeables already in the game.
Now. Armor stands would be less performant than chests, and some crafting stations–If implemented in a method that considered performance. That said. From my understanding, FC has a pretty limited dev team on Conan and odds are that this feature has not been added because more dev work keeps having to going into 'content" (i.e. DLC) to keep the game alive and making money. I think this hasn’t been done simply because there are more “pressing” matters on FC’s schedule (I mean, why else did a vanity table take so long?)
Really I think FC should take a look into this, because with as active as this thread is, there is clearly a lot of interest in seeing this happen.