Steve Jobs made Jony Ive focus solely on industrial design. Tim Cook actively encouraged Ive to lose focus, first by firing Apple’s most Jobs-like employee, Scott Forstall, and handing over Forstall’s GUI design work to Ive. Ive had no experience and no in-depth knowledge of GUI design. In addition, Cook wanted Ive to work on the interior design of Apple’s spaceship campus. All of that took focus away from what Ive was actually skilled at, which was industrial design.
Even with industrial design, while Jobs was able to manage by keeping Ive’s worst tendencies in check, Cook failed to do that.
Cook’s main skill is making astronomical amounts of money, and he knows an effective way to do that is to not care about product quality, cut corners, and give customers as little as he can get away with for their money. It benefits shareholders, but is not good for customers.