To me it feels like there is distinction between cli binaries and TUI apps. They are both user interfaces, the former in a paradigm that allows composing in scripts and shell pipelines while TUIs provide a visual stateful UI.

Both have their place. Often you'll see TUI apps being built on top of their cli counterparts, in other cases both interfaces are built on top of a common library.

What you describe in your music player example is a cli interface and imho shouldn't be in the TUI binary.