Technology commentator John Gruber is cutting about this in Daring Fireball saying: "... once [Microsoft's] goal was achieved, I don't think they knew where to go. They were like the dog that caught the car. They spent a lot of time and energy on TV. Not just with Xbox, which is alive and well today (albeit not a significant source of income), but with other ideas that did not pan out, like 'media center PCs' and the joint ownership of 'MSNBC', which was originally imagined as a sort of cable news network, website, dessert topping, and floor wax rolled into one."
It wasn't clear that the battle front would shift to portable consumer technologies, at least not to most people. But it did, and Apple set the field-of-play for that scenario. Gruber makes the point that Google developed Android as the "successful fast follower" and this was the position Microsoft missed.
Which is not to say Apple will remain the dominant player, but it will always be hugely significant, because it was the first player of any real note.
Of course, Microsoft has a new CEO and perhaps Satya Nadella has the smarts to respond better to - or even to create - changing markets.
Nadella is right that Microsoft is still (hugely) significant enough to stay in the game. As he says: "We need to be able to pick the unique contribution that we want to make." This is something Ballmer failed to do. But a deal to acquire Nokia and possible efforts to merge Windows RTS and Windows Phone is still responding to a market Apple effectively set, while Google effectively responded, leading to their current respective positions in the mobile and tablet marketplace.
But here's the thing. iPad is easy to use, and it's popular in enterprise thanks to its security features. Many people have a Windows desktop still, or at least came from that background, but now either have an iPad as well as, or exclusively.
And they come from a world in which Microsoft Office is the go-to - if not default - software for spreadsheets, word processing and email. And with good reason. They're very solid products, if not overkill for many of the uses they are put to.
Whereas Google rapidly became - and has remained - a very big iOS developer, Microsoft has largely shunned the Apple mobile platform. Perhaps Microsoft finally conceded that Apple's position of creating both the hardware and the software to run it was the right approach (for which Apple was roundly criticised, for decades). Whatever the truth, there has been a very real desire for Office apps on iPad for almost as long as iPads have been available.
Microsoft could have gained a lot from doing so (rumours have been saying Office for iPad has been in development for ages). Microsoft would have gained a strong presence on a popular device. Perhaps this would have helped its popularity. It certainly would have gained Microsoft an insight into the last decade's most enduring technology wave. Before, Microsoft had a strong presence, with Office, on a not-particularly-popular device: Apple's Mac, and seemingly with little trouble doing so, while maintaining a strong and dedicated Mac development team in Seattle.
Gates appeared enthusiastically on the brochure for the first Macintosh back in 1984, and the 'what you see is what you get' (WYSIWYG, pronounced 'wizzywig') was a big factor in the rapid uptake of Microsoft Word and Excel on Mac, and then Windows as that, too, adopted WYSIWYG.
But what Microsoft probably has in mind is cementing users to its own platforms rather than offering its software on platforms controlled by others. Lately, Microsoft has been signalling change in position since Ballmer (outgoing Microsoft CEO) said the Office version for iPads and Android tablets would come after Microsoft delivered a touch-first version for Windows 8.
Microsoft is honing and perfecting the interface of Windows 8.1x, and its related Windows RT version for touch, and rumours say Windows RT and Windows Phone will merge.
Meanwhile, PC platforms for Windows are declining, both in sales and in manufacture, with Sony closing down the Vaio line and LG rumoured to soon also exit PC manufacture.
Of course, in the 'post-PC' era that Steve Jobs declared and which Tim Cook is embracing, Mac sales have dipped too, although profit margins are so good as to create a good buffer.
But falling sales are just that. Falling sales.