[tbiteteitb]

Not necessary to upstream packages to Ubuntu Repositories when they could set their own repositories (which I assume it's how they mantain their distro)

It's a matter of branding. Which is great too as long as they keep up to date with security updates and such.

[jononor]

I don't think Canonical would look kindly on someone shipping 'Ubuntu' with 3rd-party modifications to critical system-level packages, at least without participating in the Ubuntu Desktop certification program.