I'm sorry, but you aren't using your Mac nearly enough if it's never given you problems. I've used PCs and Macs for years and I'd say they're almost identical when it comes to problems. The difference is that Windows has traditionally exposed too much of it's inner workings, which can be overwhelming and a bit turn off. But in terms of stability, Mac is no better. In terms of user experience, each OS has it's advantages.
As for the situation with updates, this has nothing to do with the number of devices and everything to do with Apple's influence. iOS 7 has been released for a total of 8 devices. While I think that there's a Lumia release overload, AT&T doesn't have nearly that many devices with a pending GDR2 update. There are only 2 devices waiting for it; the 820 and 920 which, excluding the screen, feature identical internals. Everything else already comes with GDR2.
Unlike Microsoft or Lumia, however, Apple is the one with the leverage in the relationship with carriers. And this goes back to the early days of the iPhone. Back then there was less of a precedent for how updates were handled, but the iPod was already popular so AT&T was eager to get their grimy hands on the iPhone. So they gave in to Apple's demands. Now, given Apple's market share and guaranteed sales of any new iPhone they'll continue doing what Apple wants. Android may have a larger marketshare, but no single manufacturer dominates.
So what kind of threat could Microsoft possible level at AT&T? They couldn't care less, they'd happily drop Windows Phone altogether. And this is a fundamental issue with the American retail market. Retailers of all types are in total control and they really do help shape success for a brand even as inept as they may be. The only companies able to get around all those restrictions are those with an exceedingly popular product or who offer something that can be sold via more unconventional channels.
The only way we'll ever see immediate updates like Apple is for Windows Phone to acquire a similar market share. Basically, they need to reach a point where the carriers are asking Microsoft for permission to carry their phones because currently they, along with retailers, seem intent on burying the platform.