This need to protect Windows 8 explains why Microsoft has welcomed the iPhone but continues to shun the iPad. Office for iOS represents a careful balance; it has to be good enough to encourage Office 365 adoption but not so good that it cannibalizes Windows 8's potential consumer base.
To be clear, Office Mobile will run on an iPad, but users will be forced to work in a tiny, iPhone-sized window, or to degrade the apps' visuals by scaling up the interface for the larger screen. In a blog post, Microsoft suggested iPad users will "have a more satisfying experience using Office Web Apps," the browser-based version that already allows Office 365 customers to access Office on Apple and Android tablets.
Microsoft's probably right; many iPad users will prefer the browser edition to a re-appropriated iPhone app. But Web Apps are no replacement for the real thing. For starters, they simply aren't as rich and fully featured. Moreover, they require that the user be connected to the Internet, a requirement that -- as Microsoft has recently heard from legions of angry Xbox users -- isn't always practical.
But Microsoft knows that the Web Apps are limited, and that's the point. The extent to which tablets are suited for content creation isn't completely clear, but if consumers are willing to base purchase decisions on the availability of Office, Microsoft wants these customers all to itself. If Windows 8 gains a better hold on the market, Redmond might loosen its grip. But until then, don't expect Office Mobile for iPhone to realign any paradigms, or for a tablet-optimized iOS version to hit the market.
Disappointed iPad users can take solace in one tidbit from Apple's Worldwide Developers Conference, though: An improved, cloud-based version of iWork, Apple's Office competitor, is coming.