Apple’s new CEO is a hardware guy, but software is his biggest challenge

When Tim Cook’s tenure as CEO of Apple was still young, tech-industry pundits obsessed over one aspect of his new gig above all others. After returning to the company he cofounded, Jobs presided over an incredible run of epoch-shifting products: the iMac, iPod, iTunes Music Store, iPhone, iPhone App Store, and iPad. If Cook didn’t extend that streak, conventional wisdom went, Apple’s glory days would be over. That was always a silly way to look at the situation. In 2013, two years into the Cook era, I wrote that even the Jobs years were marked as much by relentless incremental progress as b...