I often run into a situation where I have a segment in Discover that has many different segment rules built directly into the container (not just nested elements), and then I realize towards the end that I really wanted to use a different type of container (e.g. Page View instead of Visit).
It would save a great deal of time and reduce the risk of error if I could just edit the container type from within the Rule Builder wizard. For instance, where it says "Name: Visit" when going to edit a Visit container (refer to attachment for example), it would be awesome to have an option underneath that box that says "Container Type: Visit" with the option to select a different container type from a drop down list.
I could also see this being useful when sharing segments with others. They may want to use 95% of the segment I've created, and just change the container type. Again, this would be a huge time saver.