I only add anything onto the tip for decoration really, all my own bows have self nocks. I'll put on horn for decorative purposes if the bow is for someone else, but I don't think it's actually needed.
The actual force on the nock is just in shear, there is no leverage so it doesn't need much timber.
Each to his own, and they do look pretty.
Same thing goes for grips, my bows are just smooth timber, but some folk want leather.
Del