I would love easy dependency management.

It should be easy for Themes and Plugins to declare what plugins they require (as well as those they suggest), without having to graft on something like TGMPA. Ideally just comment lines in the plugin/theme's main file, Like :

/*
Theme Name: My-theme
Version: 1.0.0
Requires: advanced-custom-fields-pro, debug-bar, redirection
Wants: svg-support, wordpress-seo, wp-mail-smtp
*/

Dependency management is a huge part of software development in 2020 — entire ecosystems exist around tools like npm, composer, etc. Why can't WordPress have something sensible baked-in, like Drupal has had for years?