To have fun? Why not.
You have a Facebook profile, right? That's essentially a special-purpose cloud computer - a cloud information appliance. But, wouldn't it be cool to have an actual personal computer in the sky? Where "Facebook" or whatever would just be... a program on that computer?
You can get a Linux box in the sky, easy. But... that's 15 million lines of code you're wrangling. On a network which makes Helm's Deep look like Mayberry.
So, if it's your home in the cloud, it's not a cute little bungalow in the cloud. It's a giant castle in the cloud guarded by experienced professional elf ninja warriors. And ya know, even experienced professional elf ninja warriors, when they're off duty, like to let their hair down and not be thinking about orcs every other minute.
So if you want the bungalow in the cloud, you need basically a new programming/execution environment, and oh also a new network. So basically a new everything. So, a person could despair, or he could go build a new everything...
Could it maybe be used for something sure. But that doesn't have to be the motivation of the authors.
You don't look at art, and ask "Why did you do this??". You simply enjoy it. The artist did it, to do it, and nothing further.
If you can not see this that way, then I am truly sorry.
Tldr; this question warrants an answer from someone who knows.