Good insight, but if you discount the visual elements (tabs, buttons, etc), you're limiting TUI to CLI, and I think that's unwarranted. The value proposition of both TUI and GUI is two-fold: you see the available action options, and you see the effect of your actions. So, yes, TUI and GUI _are_ closely related: who cares whether we're displaying pixels or character blocks.

Unfortunately, they are often artificially differentiated by the style of the UX interaction: TUIs promote the keyboard actions, and GUIs prefer mouse without corresponding keyboard shortcuts. Unfortunately for GUIs, their designers are often so enamored with WIMP that they omit the keyboard shortcuts or make them awkward. I hate it when, even if the ACTION button is available by keyboard traversal at all, it requires some unknown number of widget traversals instead of being one tab away.

Since the keyboard is almost always used for the textual data, it makes sense to me to always enable it for command execution. Well designed GUIs and TUIs provide both WIMP and keyboard UX, which sadly is not the norm today, so here's my vote to make them larp for each other more.