This would not allow for the floated right button style that I think some people want. I suspect that if I were to do it this way the first question would be: How can I align my navigation to the left and the button to the right. In the above scenario that would not be possible.
The second option shown is not responsive. Foundry is built around being responsive, so that is not an option.
Most times, I would probably be happy to lose the logo.
While you would be ok with that, someone else might not. So what happens when they want the logo, site title and button, along with the navigation toggle that is always displayed?
This is just a glimpse at what has to go into thinking through adding a feature to a stack when it affects a huge swath of users.
Like I mentioned before, this is not something that will be coming any time soon as it needs to be well thought out and implemented in an elegant and easy-to-use way.