part of a groundbreaking new version of Office. Instead, the company added touch to the existing standard. The result works but is ideally suited neither to keyboard-free use nor to tablets' small screens.

For productivity, "even with a 10-inch or 11-inch touchscreen, you're somewhat stymied with the real estate available, and an 8-inch tablet just doesn't get you there," said Roy Chomko, president of Chicago-based software firm Adage Technologies, whose projects include several Windows apps.

"I have a Surface, use Office on it, and am happy to have it," he said, "but I still prefer to work on a laptop."

Though it remains broadly dominant, in other words, Office isn't as invulnerable as it once seemed, least of all in the mobile sphere.

Microsoft is "missing opportunities to monetize Office on the iPad," said Silver, adding, "There is some risk because people are getting used to relatively inexpensive products out there -- not only on mobile, but also on the desktop -- that do some of what Office does, but at a lower price."

Smaller Windows tablets can run Office, but limited screen real estate poses a problem.

"The longer Microsoft delays having a very good touch experience around Microsoft Office, the more opportunity they create for competitors to create great document editing for the iPad and Android," observed Johnson, who said he uses Google Drive to write and collaborate on his iPad.

And what about Microsoft's concern that an iPad-optimized Office suite could thwart Windows tablets? The potential is real, but protectionist tactics haven't really helped so far, and the opportunity to cash in on rvials' successes appears to be slowly closing.

More to the point, Windows tablets will never rise beyond niche use if the Modern UI can't stand on its own merits. Better to stop using Office as a shield against Apple's app superiority, and to instead focus on producing products that wow.

"People are voting with their wallets for what they want to use at work," Johnson noted. "People spend billions on hundreds of millions of iPads. It's almost as if Microsoft is denying that is valid."

For its part, Microsoft has frequently pointed to its browser-based Office Web Apps as a viable option for iPad users. The Web-based versions have gradually added important features such as real-time co-authoring, but Silver nonetheless dismissed the service as "to some extent a joke," criticizing its interface as counterintuitive. Microsoft apparently got similar complaints; this week it not only rebranded Web Apps as "Office Online," but also debuted a new interface, admitting in a blog post that the previous model was "confusing."

Nontheless, the Web versions "are not the experience [iPad users] want," Silver said.

Office's absence from the iPad is also growing increasingly dissonant with the company's recent talking points, which have emphasized cross-platform strategies. Microsoft VP for Lync & Skype Engineering Gurdeep Singh Pall spoke explicitly about the importance of non-Windows platforms at this month's Lync Conference 2014 in Las Vegas, appearing almost indignant as he rejected widely-held claims that Microsoft is too proprietary. The company also emphasized cross-platform compatibility on Wednesday when it launched OneDrive, the renamed version of SkyDrive, its cloud storage platform.

Johnson said we might be seeing a "public expression of some turmoil and disagreement" boiling behind closed doors at Microsoft's headquarters. He said some Microsoft product teams recognize they can succeed only by embracing the most popular platforms but "others are afraid."

"The result is mixed messaging," he concluded. "They've gotta sort that out."

Indeed, with the recent regime change in Redmond, the company is sorting out a number of decisions. Last year, now-retired CEO Steve Ballmer vaguely confirmed that Office for the iPad is coming. ZDNet reported this month that the product might arrive by this summer. More provocatively, it also said Office for the iPad could debut before touch-first Office apps for Windows 8's Modern UI.   

Rumors aside, this much is clear: Microsoft will likely make a fortune with cross-platform Office apps, but that doesn't mean it will sustain its monopoly-like stanglehold over the productivity landscape. To make Office the same standard bearer on tablets as it has been on PCs, Microsoft can't simply dress old software in new clothes.

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