If they wanted people to adopt a new UI, they should have not had the normal desktop exist as a weird parellel environment along side metro, and designed something that seamlessly incorporated Retro software.
That's absolutely what they *should* have done. Rather then releasing two operating systems awkwardly joined at the hip - 'Metro' for all your tablety social networking, multimedia what-not and 'Desktop' as your working environment - there should be a new, fully integrated working environment that replaces 'Desktop'.
The problem there being: they don't have one. The company is so out of position on everything
that they just don't have that side of things ready yet, but they desperately NEED to get the Metro side of things out there, and so we end up with this omnishambles of a paid-for beta release.
They'll sort it out in time, and I don't see anything in Win8 that makes me any more likely to believe that the next step is going to be the dreaded walled garden. 'Desktop' will go, but it will be replaced with a new working environment that integrates with Metro, once they actually have one.
For the time being, the fact that software you download outside of Metro only installs outside of Metro is simply a least worst solution to maintaining it as a viable working environment.
For example: I use Dropbox to back up and share my work between computers, so when I installed Win8, I searched the app store, found it and downloaded it. But that installed it into Metro! What use do I have for Dropbox in Metro? I need it in Desktop! So, I downloaded the exe from the website and installed it normally. Imagine if I couldn't have done that? Imagine if everything did install into the Metro environment? Desktop would be rendered inoperable. So, in my opinion, 'Desktop' apps installing to 'Desktop' isn't the harbinger of a dystopian future where you can only install things through the appstore, it's just that for the time being it's the only way to ensure that the two halves of this thoroughly dysfunctional pairing don't completely trample each other to death.
The thing is though, it's early days, but I rather like Metro for my social networking and multimedia what-nots. There's a chance that Valve may have shot themselves in the foot by fighting this instead of using their current influence to leverage a favourable position on the inside. I am already starting to want my games on the Metro side of the fence, and Valve seem to have decided to set up shop entirely on the working environment side of the fence instead.
The fact that I'm downloading apps from 3rd parties to integrate my Steam games into Metro rather than Valve doing it themselves seems a little farcical, and means they're losing control over how I interact with their service. And they've rather burnt their bridges now.