Ahead of Apple's Worldwide Developers Conference (WWDC) in June, there was mounting expectation that the keynote announcements would include APIs which would let third-party apps become the defaults - or at least, that third-party keyboards would be enabled.

Come the speech itself, however, there was nothing of the sort - and nothing in the followup developer sessions, and no APIs exposed in the beta.

Cue mournful faces from companies like Britain's Swiftkey, which had been hoping for a one-two this year. Its keyboard is already the default on BlackBerry's BB10, introduced earlier this year; it has been downloaded more than 10m times (and less than 50m) from the Google Play store. Ahead of the keynote, the company had high - extremely high - hopes of good news.

The reason: Tim Cook had hinted at "opening up" iOS while on stage at the All Things Digital conference in May. Joe Braidwood, chief marketing officer of Swiftkey told me this week: "We were being hopeful based on Tim's comments at D11. We were disappointed that Apple didn't liberalise its mobile OS to allow third parties to innovate the typing experience. We'd hoped this would happen, based on Tim Cook's comments at D11 that iOS would be opened up in the future."

Braidwood adds: "We're strong believers that improving the text input experience is one of the real areas for improvement in iOS, and some of the tweaks that have happened to the autocorrection engine in iOS 7 only act to underline that assertion."

Certainly over at iMore, which aims at Apple readers, a poll found that nearly 40% want third-party software keyboards on the iPhone, and that 26% said "options are good". That's two-thirds of respondents who definitely or probably would like a third-party keyboard. (If you want to turn it on its head, around 60% haven't expressed a definite desire for a third-party keyboard. But that would be hairsplitting.)

Given that apparent depth of feeling, why hasn't Apple done so? One point that Rene Ritchie makes at iMore is that having optional keyboards is the exception, rather than the rule. You can't use a third-party keyboard on Windows Phone. Nor on BB10 - the Swiftkey interface is what you get. Of course, you can't change it on iOS. Android is the only place where you can. There, keyboards such as Swiftkey (between 10m and 50m downloads) and Swype (around 1m downloads for the trial and paid versions together) certainly have their fans - though compared to an active Android population of, very conservatively, 600m phones outside China (as those in China can't access the Google Play store), a maximum of 8% of people (50m of 600m) have bothered to change their keyboard even when they can.

In fact, just as on the desktop, 95% of people don't change defaults.

Yet my understanding, from what we could call "sources familiar with Apple's thinking on the matter", is that the lack of default keyboards isn't just because relatively few people do it.

Instead, it's what could sound like a more paranoid reason: opening up the keyboard to third parties could open the platform to keylogging - which would irrevocably destroy user confidence .

This might sound daft. After all, surely you can tell if a keyboard is sending data to an outside site, as a keylogger would need to? Not necessarily. After all, if you're in a web browser, then the keystrokes that you type have to be sent to the website, otherwise nothing can happen. So what if you had a very sneaky keylogger which waited until you were in a web browser and then sent its keylogging payload to its collection site?

The problem is - the sources suggest - that by definition you can't block the keyboard from seeing everything that you type. Logically, the OS can't know whether what you're typing and where it's being sent matches the URL that you're seeing (because you can be typing inside a frame - think of the Verified By Visa frame that appears on so many transactions). And third-party keyboards would be a gigantic target for hackers who would try to create innocent-looking ones with malicious purposes.

Braidwood says this doesn't make sense, though. "As Apple specifically and meticulously approves every app update that they publish, this poses little or no threat," he told me. "Malware isn't a problem on iOS as far as I'm aware. The auto-update process [coming in iOS 7, where updated apps are downloaded in the background] would make no difference.

"The real point that we've heard here relates to wanting to protect the user's experience, which is what Tim Cook said in his D11 interview. This would seem to be framed around wanting to avoid confusion and inconsistency rather than the risk of malware. But given our success on Android we think the risk of confusion and inconsistency is a small concern versus the benefit of having a typing experience that's truly personalised and far less frustrating."

However, "little or no threat" is not quite the same as "no threat" - and it's that arbitrage Apple is keen to avoid.

In fact, Swiftkey has managed to get onto iOS - in a medical app, where the complex terminology would be tedious to spell out in full but can be composed in a flash from a few alternatives once you have a few letters. But that, crucially, is sandboxed inside the app - it can't see or record anything happening outside it.

Perhaps, the sources suggest, if there's a way to create a system keyboard which is in effect sandboxed just as an in-app keyboard is, then things can proceed. But until then? No way.

There are two ways of viewing Apple's position. You can think the malware/keylogging position is honestly held. Given that Steve Jobs was against the whole third-party apps thing in the first place (he wanted apps to just run as web apps), it's continuing its cautious approach to allowing outside companies onto the platform. Having taken years to begin infiltrating enterprises and begin to be trusted, to have a third-party keyboard blow apart a hard-won reputation for security would be disastrous.

And Apple has tightened up the security around iOS 6: jailbreaking (effectively, cracking the OS) is much harder than it ever was before. No holes seem to have been found since the release of iOS 6.1.3 in March 2013, so that jailbreakers Evasi0n don't offer a crack if you're using iOS 6.1.3 or later. (Three months without a crack is a lifetime in jailbreaking time.)

An alternative view is that Apple doesn't want the experience of using iOS to vary too much - that that might create confusion for its support people and those at mobile networks who have to deal with calls from people having trouble with their phones. (If you've ever done any sort of telephone support - even for a relative - you'll know how important it is to know precisely what software they're running. Even having a different keyboard can complicate things.)

And another view is that Apple is simply using an excuse to hang on to its position and deny app providers the chance to challenge it. After all, there's never been any evidence of third-party keyboard apps leaking or stealing data on Android, and Swiftkey and Swype have excellent reputations. Except that if you download apps from non-Play stores, you could get keylogged by a pirate copy.

Note too that Apple didn't yield in iOS 7 on the "default apps" ground either: you can't make a different browser or mail client or messages app be the default. You can in Android, but not in any other mobile OS. In that sense, Android's extreme flexibility begins to look like the exception, not the rule.

Even so, why isn't Apple allowing people to change the default app? The sources suggest that this really is a case where it's Apple's way or the highway. Apple thinks it does this stuff better than alternative offerings. If you disagree, you can always download another app (there are plenty of calendar and mail and browser apps for the iPhone) and just use those - or, indeed, try another phone. It might well sound arrogant - but Apple's approach has never been to try to capture the business of people who don't like how it does things. It's always been about pleasing those who do like how it does things. It's after that 95% who don't change the defaults.

For that reason, it's probably going to be a cold day in hell before it allows you to change the default iPhone keyboard - or the default apps. iOS 7 certainly looks different. But as far as opening it up to the outside world goes, Apple is definitely not thinking different. It's thinking just the same as it always has.