The problem for Microsoft is that they continue to serve two masters: consumer users and corporate users. Corporate IT shops, especially within certain industries, can be exceptionally wary of anything that moves data outside their walls. Consumers are in general not nearly so picky. Corporations are MS's biggest customers and for years have had considerable influence on product direction. It's just not in Microsoft'…
It seems to me that, if Apple so desired, they could make a fair bit of money selling a 'private iCloud' service to companies looking to incorporate iPhones and iPads into their infrastructure in a big way. In the same way companies can set up their own BES server to provide in-house management of their data, the ability to set up an in-house iCloud server, to back up their employees' documents, data, settings, etc.,…
I think they just don't have the capacity to do more big things right now. When/if iOS gets put on medium heat like OSX is/was, then maybe we they'll try this. It's not really much harm waiting a few years to see if/how some of the newer Apple stuff (iOS, icloud) and its competition gets used by large companies.