From this article:
"Because Jobs was such a powerful, brilliant executive, his flaws tend to be swept over. But he had flaws. For instance, he was opposed to putting iTunes on Windows-based computers. However, that was the right call as it led to widespread adoption of the iPod, which kick-started Apple’s comeback. Jobs was opposed to an App Store because he wanted total control over the iPhone’s software. The App Store was the right call.
After Jobs died, I spoke with a former Apple executive, and one thing he said has stuck with me. Basically, Jobs created bottlenecks at Apple because every major decision flowed through him. With Jobs gone, and power more diffuse, it seems as if Apple can do more within its product categories.”
See? Steve Jobs was great but in retrospective can be seen as hindering Apple advances in many ways.