Drupal is a mature platform fighting to stay relevant in a new generation of web systems.
I think Drupal solves content management problems in a very robust way.
But, the admin, user, author, owner, designer, manager, and developer experiences could all be improved.
Here are some things I think would be huge wins.
AI Site Builder
We have a system that can be built with config files that AI could generate based on a conversation about what you want.
Better Layout Builder
A slick UI that is enjoyable to use.
Content usage and reports
A way to inspect what's in a site, how the content types are being used.