Thank you for the feedback, This is a request for SharePoint in general. we are looking at this in general for SharePoint and the SharePoint migration tool will support it once SharePoint supports greater size
Every 0365 teams sites are connected to a SPO site collections You can therefore go to that site and migrate to it if you are the site admin.
We are working on new improvements to make moving to Teams even easier.
Thanks for the feedback. we are considering on how we might make that experience better.