The first suggestion is a minor thing that has probably been mentioned before, and may even be planned. I'd like to see leather items require different amounts of leather, and not use up a whole leather stack if they don't require it all.
For example a piece of leather torso armor might require 5 units of leather, so you could make one out of a single bonobo skin or a third of an elephant skin. I get annoyed that a raccoon skin can make the same amount of armor as an entire dragon skin. I should at least be able to get a full suit of leather armor out of a dragon.
I imagine this is not a priority, and would probably be best implemented after stacking improvements have been made. Since this would effectively increase the amount of leather gained from large animals, it would probably be best if it waited until animals required food to survive.
And animals requiring food to survive brings me to the second thing I'd like to discuss: animals should require food to survive. Naturally, most herbivores would be penned up outside where they can graze on the local flora during the warm months. Cats could survive by eating vermin, though other carnivores would be realistically expensive to maintain. Milling grass crops (like longland grass or some new animal feed crop) could produce fodder for winter survival.
Before animals start taking up precious food resources, it would probably be good to include an auto-butcher option for animals above a certain amount. Animal pens would provide a solution to the annoyance of masses of animals swarming the meeting hall, though non-butcherable pets that need to be fed would become an even more onerous burden. To make feeding large or carnivorous animals worthwhile, it would be cool to make them war-trainable by default or usable as mounts.