First - but we already knew that - there is no technical reason preventing desktop applications from running. There are no inherent limitations in Windows RT compared to Windows 8. All that's standing between you and freedom on Windows RT's desktop is an artificial limitation by Microsoft.
Microsoft's somewhat official reason is that it can't create an emulation layer fast enough to run code compiled for x86, and they are probably right. The underlying argument here is that Microsoft wants to shield users from downloading software only to find that it doesn't run because it's x86. However, there's an obvious flaw here.
You see, there's no difference between the application not running because Microsoft prevents it, and it not running because it's x86. In both scenarios, it won't run. The user is frustrates. If Windows RT's desktop mode was open, lots of developers would surely recompile/port their applications, making Microsoft's concern far less of an issue.
Security is another major concern, and here Microsoft has a point. A Windows that can't run x86 code, but only Metro applications, is a safe Windows. Opening up Windows RT would make it vulnerable to newly written ARM malware.
All in all, Microsoft will not allow easy jailbreaks to exist, let alone provide an official method to do so. The reason is simple, and has nothing to do with the above: market segmentation.
Windows RT is supposed to be for cheaper tablets, while Windows 8 is for more expensive tablets with laptop-like performance. If popular desktop software got ported to Windows RT, Windows 8 tablets would lose their major unique selling point. A lot of Surface buyers who want a Surface Pro now, would opt for a Surface RT instead.
As such, I expect Microsoft will do whatever it can to prevent jailbreaks - and it will certainly not provide an official method. Microsoft's statement reflect this.
We applaud the ingenuity of the folks who worked this out and the hard work they did to document it. We'll not guarantee these approaches will be there in future releases.
So, the company is indicating the issue will be 'fixed', and gives zero hints about their policy ever changing. In other words, don't rely on hacks like this - if you need real Windows instead of My First Windows™, you'll have to go x86.