Quote from Cruncheon
If we could just build a saddle out of easy materials, that would take the fun out of it. You find a saddle in a chest, and then you think "Wow, think of the possibilities!" Then you go on an epic adventure to find a horse, ride it back home and think to yourself "Yup, worth all the effort." If we could just make saddles easily it would be unbalanced slightly.
Actually, under current circumstances, craftable saddles would still be balanced. Horses are very rare already, so really, it's just making half of owning a horse less rare, which is actually a good thing since horses and their gear are both/will be pointlessly rare. Pig riding is mainly a novelty, and carrots are rare for those who want to control it with a carrot on a stick,