But the opposite could be argued as well? Taking on a new disruptive problem is a huge risk, and big corps are generally risk averse...

Depends on the company - in a company like Amazon where Jeff is constantly pushing the envelope - standing still is the best recipe for falling behind. And you can see a hint of this happening in the article itself - the person running Books is given the reward of commoditizing Books as the reward of doing a great job of running Books. All the glory is in delivering new bigger and better things to Jeff, not in incrementally delivering 10% year over year improvements on an existing problem. In fact in such companies it can become difficult for managers to attract and retain ambitious talent to work on "incremental" things.