I'd like to have nested projects as well. For instance I want one top-level having my talks, and then sub projects for each talk. Now I either have to clutter my repos with many small projects, or have one big repo with many folders. Which I don't like, as issues, comments, stars etc. should be directed directly to the talk, not a big project. Other top level projects would be one for various PoCs, learning different languages, programming competitions, maybe one for stuff I did at university etc.

Same for organizations, where I work we now have hundreds of repos in a flat structure. Impossible to manage.