I’ve run into several situations where it is necessary to be able to create a nested collection of lists. I’m sure there may be other ways to change things within a list using filters and such to try to approximate a nested collection. However, I think this seems a bit janky and not ideal. After all, while using nesting does indicate a relation between items in the structure, it doesn’t mean that all the items in each node (i.e. folder) of the structure should therefore be crammed into the same folder or list (which is how it is now).
I just think that having the ability for users to create nested folders and being able to put their lists into these folders (including having the ability to freely move them into a different folder after they have been created) would allow a lot more flexibility and easy-of-use.