Here's a funny story. DotCloud's early prototypes were in fact
very similar to Cloud Foundry's "paas-in-a-box" project. We even open-sourced large chunks of it.
We eventually had to drop that design because, beyond a certain scale, it gets in the way of the user experience - in a major way. I think all major PaaS providers will agree with me.
You have to chose your priorities. Ours is to make developer's lives easier. We axe everything else.