A. I don't know how you posted this without getting flamed.
B. I have posted in several threads always resulting in troll attacks about not having 4 feet to nail the horse shoes too.
C. You forgot the usual defense I post, pay 100% to make the item slotless or pay 50% more to have the item in a different slot.
A. That's you. This is me. Also I didn't go into how to wear them, merely to UMD away the horse requirement.
B. That is front loaded with a few assumptions you know that? For instance, if horses have four feet then how come they can only benefit of wearing a single pair of boots? How can a horse benefit from wearing gloves if they have no hands or fingers (well dragons can and their front limbs are "feet")? If these shoes do in indeed take up four feet's worth of slots, then a four legged creature couldn't wear them to begin with. Also, not all shoes are nailed on either (some were glued). In fact, the hipposandal would have been called a horse shoe (whos going to argue what sandals are?) around the 1100s; the same time period as D&D's Greyhawk world is modeled after. Maybe they are four metal U shaped pieces of metal you have to nail on, maybe they didn't. I don't care, and that is probably another difference between you and me. To me, what matters is limits and usage of Magic Items Worn flat out ignore common sense and practicability to begin with. Not to mention...
C. Wouldn't Polymorphing into a four legged creature be easier than resorting to the DM's Crafting rules? Like idk, a Dire Turquoise for free pre-surprise rounds? If four "legs" would have shut them up, polymorph into a dragon and bite their heads off, then turn into a Legendary Bear and maul the remains. What can they follow up with? Nails in the toes hurts, take 1 damage per round (same as being stabbed with a nail for torture)? Pfft, for +10 Int & +6 Cha as a caster, my casters would pay an arm and a leg. Really, slice them off, gone, no more, want the other leg too? That's are great those bonuses are.