See, I think people are confusing antiquated gameplay and open world mechanics with different levels of accessibility. If you compare Witcher 3 to Horizon it makes Horizon look 'antiquated' to some people. Witcher 3 is chock full of Side Quests, which can be overwhelming to some and Breath of the Wild sparing uses its placement of side quests similar to Horizon actually.
I think Breath of the Wild is way more approachable for more casual gamers than Witcher 3 by a mile. I'm not saying it is a casual game, its just easier to get into and learn than Witcher 3 and its plethora of controls, abilities, locations and meandering story which may take you time to get back to between doing 20 side quests.
I'm writing this as a fan of all 3 games and the way they treat players. I just wouldn't call anything Breath of the Wild is doing 'antiquated' just different. It's approaching its accessibility a different way to either Witcher 3 or Horizon.