If you've ever had to scale capacity on AWS (or any other on-demand cloud service, really) you'd know. On the page they say 300 seconds to bring up a Linux instance, but really that can even take longer from time to time.
When you need to scale in a hurry (or in this case semi-automatically), the ability to launch persistent or temporary VM instances in a much shorter timeframe is critical.
Granted (and as they note here) this is sort of demo-only, and probably not particularly useful out of the box. But as a demonstration of how fast things could work it's perfect. It doesn't hurt that it's functional.
When you need to scale in a hurry (or in this case semi-automatically), the ability to launch persistent or temporary VM instances in a much shorter timeframe is critical.
Granted (and as they note here) this is sort of demo-only, and probably not particularly useful out of the box. But as a demonstration of how fast things could work it's perfect. It doesn't hurt that it's functional.