"It's a question of which skills are most highly regarded. Everyone has different strengths, and the people who are going to build the next Twitter aren't necessarily going to build the next BigTable as well. A culture that has been very successful with one strength can have difficultly recognizing others."
— former Googler Paul Buchheit
Indeed, this explains why Google and Apple have almost entirely complementary product lines. They're all in it to make money, of course. But Google's culture is built of people who love tools and hacks. Apple's culture is built of people who follow Steve Jobs; and Jobs is by nature a dictatorial art director, whose art forms are luxury consumer gadgets and corporate imagery.
iOS and Android are fully complementary in philosophy, though it's easy to miss how different they are since their facades are so similar. Jobs has a vision of the art piece that is the iPhone + iOS, and he deeply and personally resents any compromise of that vision. Did you see the press conference in which he gave users free bumpers for their iPhone 4s? He was not contrite, trying to win back the unhappy customers and repair Apple's image. He was *pissed* -- not at his antenna engineers, mind you, but at the *users* and the *press* who forced him to put a rubber bumper around his magic sculpture. And he makes no allowance for alternative implementations of either his hardware or his software. They are what he sells you, and they do what he sells you, and if that's not good enough for you, he'll happily tell you to fuck off. Sure you can have apps in your phone, but their icons will be THIS big, they won't touch each others' data, and if he thinks his (his!) store is worse off with your app in it, well, again, he will happily tell you to fuck off. The only magnets on his refrigerator are the ones HE likes. (One camera app got booted for using the side buttons to take pictures. How dare they?! The side buttons are for volume!)
In contrast, every aspect of Android is as open as the carriers and a decent security model allow... Not because Google is altruistic, but because Google is populated with people who like that kind of thing and believe in the collective mind, the unplanned and unscheduled group accidents that make magic. And fart apps. But when you're managing a Google-like zeitgeist and try to squeeze a consumer appliance out of it, things can go horribly, horribly wrong. Case in point: Google TV and its remote from hell, the worst example of The Inmates Running The Asylum I've seen in a decade. "More buttons? Sure! We can just crowd in closer to the primary wheel control ...." "Works for me!" So sad. But what else can one expect from an organization that implements customer support in Python?
Granted, Mac OS doesn't really fit the Apple paradigm as well as iOS -- yet. Sure, Steve couldn't pass up the price tag of $0 on FreeBSD, so Mac OS X is a good OS even by engineering standards - solidly designed (if not well-patched), and fairly open. But it's way too open for Steve to be happy. Mac OS Lion will have an app store. The writing is on the wall for Mac OS X -- and recall that in the Biblical story that gives rise to that phrase, the writer was God, and his VPs knew better than to argue.
Google is now suffering from the early stages of Microsoft Schozophrenia - the tendency of groups and divisions without strong connections to central leadership to go off and do things on their own which end up being unsuitable for corporate adoption. They end up either poorly integrated and dying of neglect, or killed outright. The examples from Microsoft are legion, of course. As for Google, Wave is just the most obvious example, but I understand that many cool things inside Google just don't make it. For example, there was a real estate listing plugin for Maps. It worked, it was very effective; but for whatever reason it didn't attract users, and it was simply allowed to die. No plan; no vision; just stuff that happens. It's more like an open source community, for good or ill, than anything to be found in Cupertino.