It's nice but it still doesn't fix the issue with people who have medium end machines where you develop in a VM full time and want to be able to run a VM within a VM.
For example with fairly old but still reasonable hardware you cannot run virtualbox inside of an existing virtualbox instance.
If you have a windows box and develop full time in a linux VM you cannot run vagrant inside of that linux VM because unless you have a modern CPU it lacks the instruction sets required to run virtualization within virtualization.
Now using docker instead of a VM would work but docker only supports 64 bit operating systems so anyone stuck with a 32bit host OS still can't use vagrant and has to resort to using raw linux containers without docker which is really cumbersome.