Consistency, consistency, consistency
When someone starts writing it's not unusual for them to want to creative, to be un-boring, so when they have a character talk, that character "intimates", "whispers", "suggests", "exclaims" and otherwise enjoys every imaginable bit of literary variance the author can throw at them.
More seasoned writers tend to just stick with "said". When a character talks, it's "said", "said", "said". Over an over again. Page after page. Turtleneck after jeans. "Said", "said", "said". It's used so often it just disappears, the mechanics disappear, the author disappears, and all that's left is the character.
Apple's iOS has a pretty consistent user interface. It's not perfect by any stretch, but it's more consistent than its competitors. Occasional page curl in Maps aside, the basic ways you move around the iPhone are the same, Apple app after Apple app. (And anything that's not tends to get hidden away so power users can "discover it" and mainstream users can live their lives never having to be bothers by its existence).
iOS is so consistent, so single minded it being consistent, that when it isn't -- especially when 3rd party apps aren't -- it causes problems. Upper left had corner is a virtual back button. Tap and you go back. Tap and you go back. Tap and you... are suddenly editing your account? That's the type of exception that proves the rule. You're so used to doing something, it's so instinctive to do certain things, that when they don't happen you notice, and you get annoyed.
Beyond the UI it applies to Apple's platform as well. From 2007 to 2009 every iPhone and iPod touch -- 6 devices not counting re-issues -- not only ran pretty much the same OS but had pretty much the same specs, the same screens, the same types of chips. When newer, better technology was thrown in -- GPS, 3G, faster chips, more RAM, iOS abstracted them through API like CoreLocation so they remained broadly consistent. In 2010 Apple added the iPad which admittedly muddied the consistency waters, but they made sure it could run iPhone apps either 1x or 2x in double fuzzy chunky mode. iPhone 4 quadrupled the resolution but kept the same size so old apps "just worked" with 4 pixels instead of 1 if they had to, and the new gyroscope got hooked up to the old accelerometer and CoreMotion was born.
When speaking of the iPhone and the iPad, Apple SVP of design -- and again, how many hardware/software companies have an executive level designer? -- said he did everything possible to get the device itself out of the user's way. It's just a screen. Apple's software designers have done a little of the same. But maintaining consistency to such a a consistent degree, a significant part of the OS gets out of the user's way as well and only the content is left.
Say what you want about the iOS home screen being a boring old app launcher, but it's always a boring old app launcher, swipe after swipe, page after page. It's not a card view one moment, app launcher the next, wave in between. It's not a bank of widgets arrayed like Hong Kong street signs surrounded by empty spaces and the occasional app in between -- if they've been liberated from the drawer.
iOS consistency is so prevalent it becomes easy to overlook, but just spend a few days with another platform and it you start to realize it almost immediately. Incredible variations in hardware and UI skins are great for varieties sake but usability takes a huge hit.
Just for fun I passed around a few non-iPhone devices to co-workers, all smart techies. It took them a while to do even basic things like turn them on, unlock them, find Wi-Fi and add the password (note: never have two buttons for Wi-Fi one on top of the other where the first one turns it on and off, they'll hit that one every time while looking for the settings hidden in plain sight beneath it.) I watched in particularly horrible fascination as a friend of my went to Digg's mobile site, tapped a link, and had the device activate the link below it. He repeated and it did it again. About 4 out of 5 times when he hit pretty much the same spot -- a link -- it would trigger the one below. And yes, only 4 out of 5 times, just to be inconsistent about the inconsistency. Finding the phone to place a call? Woz wasn't wrong. It was comedic at times.
In stark contrast I've mention numerous time how I've given iPhones, iPod touches, and iPads to children as young as one and half and they've been able to unlock them and launch the apps they wanted to launch. At two and half they could use it well.
That's the power of a fairly consistent platform running fairly consistent consistent software.
It's what Apple has been doing for years, for decades -- making software and focusing on human interface (they've even got guidelines). It's why feature checklists might not be the best way to measure advances in the smartphone space (though every June Apple takes as good a jump down checklist street as anyone.)
Microsoft is reportedly laying down the consistency law for partners with the upcoming Windows Phone 7, and rumor has it Google might try to divest itself of all those Android UI skins with version 3.0.
Sure, "power users" might get bored but we complain about everything anyway. People who just want to use their device won't even notice -- they'll be too busy using their device. Just like readers are too busy enjoying their novel and don't give a second though to "said", "said", said."