This feature would allow you to create a space between handwriting and images that have been placed on a page, allowing you to add more information.
For example, let's say you have a numbered list:
1. Add eggs
2. Bake
And perhaps you want to add something in between number one and two on the list, instead of having to erase number 2 or lasso it and move it down, imagine if one could simply tap between the two and push it down, similar to a feature that exists in onenote. This would make rapid edits and changes to a document so much easier, especially in large documents where your edit may require pushing down a significant amount of text.