Stuff like this, that has zero effect on gameplay but players would love to have for style's sake, are a valid reason to do DLC. Not an expensive DLC- but if you sell a few thousand of these at $1.99 USD or so, that will make it worth the cost of having the dev team do the work of creating said walls.
I would however like to see "log cabin" walls made from core wood, as the game literally says that about core wood. Should have more hit points than standard wooden walls, as is the case IRL. Core wood is only available in the Dark Forest, so it seems balanced to me.