You can ignore those instincts and increase the horse's stress and discomfort, however the smart handler sets the situation up to use those instincts in a way that that advances the gentling process and avoids situations that generates fear and defensiveness. Your wild horse does come with a number of advantages. He's not spoiled. He hasn't figured out how to run games on humans. He's not been abused or mistreated.
Wild horses are incredibly adaptable.
Your wild horse is now in a new, strange environment. This provides an excellent opportunity for you, the adopter, to put your best foot forward and show the horse that his new situation isn't really so dreadful as well as encourage him to learn about the benefits and pleasures of domestic life. Most adopters don't have round pens. Even of those who do, most people don't have the timing and sensitivity to effectively work a wild horse in a round pen. The tempo in the round pen can quickly accelerate to where all the handler is doing is reinforcing the horse's instinct to run from the human.