I don't know what a TUI is (i'm guessing "terminal ui" as if the term CLI doesn't exist lmao) but yea, they could have put effort into their product and not forced people to use their atrocious ncurses interface which is like the worst of all worlds: text interface without the benefit of the shell, zero accessibility.
CLI refers more to non-interactive programs used through a shell, programs like grep or or indeed the `claude` program in non-interactive modes. TUIs (text user interfaces) refers to interactive programs implemented in a terminal interface, what you call ncurses interfaces (but usually aren't implemented using ncurses these days.) They're GUIs in text, so TUIs.
Anyway, their decision to implement a TUI was definitely not done out of laziness nor even pragmatism. It was a fashion choice. A deliberate choice to put their product in the same vibes-space as console jockey hotshot unix pros who spit out arcane one liners to get shit done. They very easily could have asked claude to write itself a proper GUI interface which completely avoids all the pitfalls of TUIs and simplifies a lot of things they went out of their way to make work in a TUI. Support for drag-and-drop for instance, isn't something you'll find in many TUIs but they have it. They put care into making this TUI, the problem is that TUIs are kind of shit, and they certainly know that. They did it this way anyway effectively for marketting reasons.