The decorations are cute but they have a cost and no effect so they are purely cosmetic. It might be interesting if they gave a small bonus to nearby tiles, something to encourage sprinkling them in and encourage more diverse outposts.
Some examples below...
Lamp: Increases resolve by 1 during the Storm for any villager within 3 tiles.
Flower Bed: Increases resolve by 1 during the Clearance for any villager within 3 tiles.
Road Sign: Increases move speed by 5% for any villager within 5 tiles.
More of a stretch and bigger change could be making walls matter. Could have wood walls and stone walls. The effect could be any villager within enclosed walls could get 1 bonus resolve.
I feel like this change could leverage existing decorations and hopefully not increase the complexity too much. I am imagining that you might place a road sign at a frequently traveled cross road since it would give the greatest bonus there, kind of like placing an AOE damage tower in a tower defense game.
We added some more meaning to decorations in the Hubs Update (eremitegames.com/hubs-update/) - they now contribute to HUB progression, and indirectly lead to resolve and production bonuses. It's by no means a perfect/final mechanic, but we will improve upon this system. I think it serves a purpose close to the one suggested here, so I'm moving this suggestion over to "done".
I also never build these because they have no function. Even something as simple as resolve bonuses to villagers living or working nearby (which I suggest because it's obvious the game tracks these things already) would be great. Even if it is small.
I use them to fill in awkward grids, maybe be neat idea if they affected adjacent buildings in some way, like barrels adds capacity to the building, or a gate adds a different entrance for the villagers into work buildings
That would be a great idea. I have a bunch unlocked but i never use them, largely for that exact reason. I'm happy they exist, but given the limited map space and their lack of function i usually can't justify building any.