Overall, I think that Apple’s Human Interface Guidelines are a set of very well-thought out, deliberate, precise, design recommendations. I feel that many of the points described were tried and true good practices. They champion apple’s design philosophy of valuing content, functionality, and interactivity above all else. Apple believes that great UI design enhance a user’s understanding of the content, rather than compete with it. A focus on functionality should motivate the design, and keeping appropriate elements interactive or familiar can make users feel like they’re in control. I get the sense that for Apple, the best human interfaces minimises extraneous thinking on the part of the user. Designs are meant to be understood right away, in the subconscious. Too much mental effort on the part of the user ruins their experience.
What these guidelines do is help Apple devices maintain a comparable experience in all contexts, so that the user experience in the Apple ecosystem is consistently smooth and expected. It is part of Apple’s brand identity that customers associate user-friendly design with apple products. I personally believe that standardisation in interface design is important for users to the extent that it doesn’t overly limit creativity. It is still possible to conform to people’s intuitive expectations without following preconceived design guidelines. While guidelines are great for those clueless as it sets a benchmark for user-friendliness/usability, it should not restrain those already familiar.