The problem is that this utility defeats the battery life savings which is the main point of the metro "one app at a time" model by breaking the suspend/restore functionality by enabling you to run many concurrent applications.

It's very likely that this utility also breaks some of the sandboxing of metro applications, introducing security vulnerabilities that don't exist in vanilla Windows 8.

That said, this utility looks cool, and I hope Microsoft encourages, rather than discourages, stuff like this going forward. Let the power users customize the environment however they like.

But there are good reasons that they don't enable this out of the box.