Hey @Sash!
Firstly - thank you for taking the time to share your experience and POV. Your passion for wanting to see Studio succeed is evident.
From my own experience, Responsive AI works best when no layout tools have been used (simply dragging and dropping elements into the rough area you want them, without grids/flexbox/stack etc).
If you have any links to these templates that are not working as expected, I’d love to have them for the team to review.
Are you working with different breakpoints in headers vs the page?
If you haven’t seen it yet, I would encourage using the dedicated bug reporting flow that can be found here - Wix Studio - How to report a bug - it’s a slightly different flow to the ususal Customer Care experience 
I’ve shared this feedback with the team, and as I said, I value the time you’ve taken to share 
We announced back in April that creating a Studio version of a clients’ Wix site was in the works. (Preserving the dashboard and data, but creating a branch of the site in the Studio editor). We’re in the final stages and will begin rolling out this option in the coming weeks. While I understand this was a top feature request since the launch of Studio - I’m excited and proud to see the community have an impact on this feature.