The Barn is currently so far into the building skill tree that it takes a skilled mason before you can unlock the structure. However, someone leveling animal lore and procuration has access to the barn much sooner in their skill tree.
It seems a little unbalanced to me at present.
In ancient and medieval times, even very simple farmers and peasants often had swine, goats or sheep and kept them in simple enclosures.
Perhaps we could add a new wooden animal pen (similar to the wooden well we now have) that is accessible in the construction skill along with either the coop or stables. It could be a 2x2 or 3x3 pen that maybe looks similar to the wattle fence, with some hay or food bin inside or maybe even a small simple shelter inside for the animals.
It would allow access to these animals at a much more reasonable time, provide another option for base layout, etc. and add a nice realiztic option to the game.
To add to the value of barns, perhaps animal quality or capacity can be limited in the new pen, so that the preferred option is the barns still.