For me, less distracting and confusing visual clutter on the screen. Also, the pane showing the file hierarchy is redundant with the file explorer that the OS already provides. But either way, not having to use an IDE is a blessing. Especially on a 14" touch screen laptop.

Note that I'm probably a freak, lots of my friends love their IDE's, but having having something that works for my particular brain and my eyeballs is a blessing.

You describe the use case for vim, not notebook. Use vim and jupyterlab. It makes working on several projects much smoother.