@DeathByVisualStudio: And when did I say it did? I explicitly said the sidebar thing is not a Taskbar but more akin to an MRU list. And that trying to bodge on things like Close buttons or Jumplists in order to turn it into one doesn't make sense. I know you love to disagree with everything I say just because I said it, but a least make some effort to be consistent, eh.
@Bass: It's not just about killing apps, it's about the entire process lifecycle. From what initiates it to how it has to behave whilst 'running' right through to how it ends (regardless of whether voluntarily, at the users request or at the behest of the system itself),
@Sven Groot: Which is why Remote Desktop makes little sense as a Metro app and, as far as I can tell, only exists because Windows RT devices might need to connect to other systems remotely. It's not because the principle itself is unsound, but more because Metro tackles the "low hanging fruit" part of the problem and deliberately avoids the more challenging areas (which is simultaneously why you can't run Metro apps windowed, because you reintroduce the problems that were being deliberately left to one side till a future version)
There's no reason that in a desktop environment where application lifecycle is managed by the system, you can't maintain some semblance of "state" based on the fact an application has a window open, indeed to some degree you need to anyway (much as Metro would never suspend the foreground process). That doesn't mean that it's necessary to start every application manually (so Messenger could still inform you of a new IM without you ever having to explicitly end it and Outlook would always pop up your reminders regardless of whether you remembered you need to open it to check) Nor does it mean that closing the last "open" remote desktop windows has to actually terminate the underlying process, the OS would be free to keep it "hot" if it didn't need to relinquish the resources in case you want to use it again. The point is to free the user from unnecessary resource management, not to prevent them saying "these are the Tasks that are important to me right now"