There are many other benefits to unikernels especially depending on which implementation you choose to go with. For example, MirageOS and Rumprun are good examples of clean-slate vs current systems. I'd recommend reading some of the articles at http://unikernel.org/resources to get better view of this.

As for 'a user friendly mechanism like Docker' ... well, I hope today's news convinces you that it's in progress.