When I read, first in tweets, and then in Marco Arment’s post today, that he’d commissioned an official Instapaper app for Android, I had this nagging sense that I should be more interested in it than I was. It took this seemingly unrelated post about Office² by David Sparks to make the connection for me.

On the face of it, Instapaper for Android should hold no interest for me at all. I don’t have an Android device and don’t expect to ever get one. And although I’ve recently been using Instapaper more than I have in the past—credit this Macworld article by Eddie Smith for that—it’s not an app I’d miss terribly if it were deleted from my phone. When I sit down to read my RSS feeds and Twitter stream and I run across an interesting link, I usually just read it then and there, because that’s what I’ve set aside time to do.

But look at what Marco said about his change of heart on Android:

Simply put, Instapaper needs to be on popular reading devices. That category now includes at least three 7” Android tablets, probably with more to come. I realized last winter that I needed to address this demand…

The logic is impeccable. Instapaper’s mission is to make reading things from the web easier, and therefore “Instapaper needs to be on popular reading devices.” There’s a straight line from A to B.

David’s post about Office² got me thinking about Microsoft. Microsoft’s mission used to be just as clear as Instapaper’s: Microsoft makes the software that runs microcomputers. It’s a much bigger mission than Instapaper’s, of course, but it’s no more complicated. And that simplicity of purpose is what drove Microsoft’s success.

Why, then, is Microsoft Office not on the iPad? Why is there a void for apps like Office² to fill? It certainly can’t be that Microsoft is unable to write MS Office for iOS. The app might turn out hideous and clumsy, but it could be written.

One popular explanation is that Microsoft doesn’t want to promote a non-Windows operating system—that it believes keeping Office exclusive to Windows 8 will give 8 the boost it needs to gain marketshare. This could be the reason, but if it is, it demonstrates how far Microsoft has drifted from the straightforward purpose of its earlier days.

In the 80s, Microsoft didn’t shy away from developing for CP/M, the Apple II, and the Mac. It didn’t keep its application software exclusive to DOS to give it a competitive advantage. Apple sells microcomputers, therefore we will make and sell software that runs on Apple computers. Hell, when Excel came out, it was a Mac-only product.

I suspect Microsoft is split internally between the traditionalists who want to make Office for iOS (and who may well have already made it on a contingency basis) because that’s where the market is and the Windows 8 people who want to keep Office for themselves. If a decision is being held up as this fight plays out, that favors the Windows 8 faction.

It also favors apps like Office². And it teaches iOS users a lesson that Microsoft certainly doesn’t want them to learn: that they can get along just fine and do lots of useful work on their iPhones and iPads without any Microsoft products whatsoever.

To be sure, there’s no need to have a bake sale for Microsoft; it’s still a highly profitable company. But if it wants to regain the momentum it had 10-20 years ago, it needs to return to the single-mindedness it had back then.

Maybe Steve Ballmer should ask Marco for advice.