Stuff like this is so convenient and intuitive that it makes you wonder why we didn't start here in the first place!
One thing I wonder is how many data scientists will use this feature given that it is not enabled by default (which is understandable, would be messy for every notebook to have a venv), and only via command-line arguments.
I guess this is easily remedied by helpful beginner tooltip UX ("This notebook has several dependencies. Would you like to build it in a sandbox?").