Google is famously managed by engineers with a strong emphasis on engineering as a company value (whether they actually live up to that is an entirely different discussion). Apple famously holds design and designers in high esteem.
Microsoft? For the past 10+ years Microsoft has been managed by their Salesman in Chief. Ballmer was a sales guy with an MBA. A lot of Microsoft's defenders love to point out how Windows is still the best selling OS in the world or how Microsoft's revenue numbers have done nothing but go up over the past ten years. To take these statements at face value and out of context of what the rest of the technology industry has done since Ballmer has reigned at CEO is extremely naive and short sighted.
Ballmer did what sales people do best: he sold their existing products. Sales people do not create. They take products that have been created by others and through social skills (which Ballmer arguably had) persuade others to buy. But when you then take a person such as this and put them in charge, it can have disastrous consequences. I would argue that people with a sales background are very badly suited to run a technology company. Now, that is not to say that a person with a sales background can't make a great CEO - I'm sure there are many who have founded and ran great companies such as Macy's, Sears, etc. No, my argument is that sales people do what they do best, and that primarily is protecting their existing territory while trying to sell as much of it as possible. Microsoft has essentially been playing defense since Ballmer has taken over. And their weapons with which they've defended with (Office & Windows) have slowly began to lose their effectiveness. Microsoft cannot defend forever, especially when Google and Apple are both on a warpath. Microsoft has been crippled for years. There are dozens of stories of creative products that began to get traction within the company, only to be squashed by the Windows or Office divisions as soon as that product started to look like a potential threat to their sales. Countless stories tell of political fights within Microsoft between those two divisions and how the bureaucracies of those two products would shut down or cripple any initiative that they perceived as a threat to their own budgets.
One prime example of this is the Courier project. In case you don't remember, Courier was Microsoft's early potential answer to iOS. A team within the company had developed a new touch interface that ran on a touchscreen tablet-like device. It was so far along that a demo video was leaked onto the web which received very high praise from most designers who saw it. When the Windows division found out about this, they used their political clout to have the project shut down because it did not run Windows. Most of the Courier team quit Microsoft to founded their own company. You can now see the fruits of their labor on the App Store, known as Paper. In fact, if you browse their company's about page you will see a who's-who of ex-Microsoft employees who all have innovative iOS and touch products to their name while at Microsoft who now no longer work there.
I do not know if Steve Ballmer is directly responsible for the fact that 53 exists, as a company, but surely if he is not, then his failure to prevent others within the company for driving employees like this out can be laid as his feet. Ballmer's corrosive policies has propped up the bureaucracies of Office and Windows at the expense of all other creative initiatives because he is too short-sighed or cowardly to attempt anything else for fear that it could harm their crown jewels.
The sad part is though, as John Gruber pointed out, all of the potential successors to Ballmer that showed any promise have all left the company in the past several years. From the outside it looked as if Ballmer himself was responsible for driving them out of the company for fear that they might replace him. And now, in the end, it looks as if even that couldn't save him from being forced out by the board. Good riddance.
If there ever was a time to bring in someone from the outside, and to not promote within, I think this is it. Ballmer has seen to that.