The arguments for shoeing horses have manifold foundations.
Obviously many of the arguments from the farriers world are financial and economic oriented. Farriers are afraid of losing their livelihood and consider that they are the only people qualified or with sufficient knowledge to work on horses feet. Sadly, Most farriers still ply their trade using outdated, and sometimes downright misguided, knowledge. The problem is that this knowledge is also propagated by the veterinary world.
Veterinary surgeons and specialists are also still learning the same outdated and misguided material that they were learning 80 years ago when animal doctoring became a protected trade and the veterinary surgeon was principally a horse surgeon.
The veterinary education is principally biology oriented. But the shoeing of horses has a major effect on the bio-mechanics of the horse. This field is studied too little because of the distance that is maintained by the two disciplines of biology and physics.