Horse hair sporrans were quite common, even for casual wear, until about 50 years ago or so. These days you see them worn mostly by the military and pipe bands. But if you like the look of a horse hair sporran, go ahead and wear one!
One thing to be aware of is that horse hair sporrans don't usually have a pouch built-in for your stuff. Most of them are purely dressy rather than functional. But all of the horse hair sporrans we offer have the option of a pouch (recommended).