I actually was a Cursor advocate / CC hater (go back in my comment history), and now I use only TUI coding harnesses.

To start a big part is just the efficacy of them, which comes down to the model and the harness logic itself. CC is good, it's sub-agents, loops, background jobs / agents, skills/hooks/etc have typically been pretty far ahead though others are constantly catching up.

But you're sort of missing something. I use iTerm, so to me it's not the TUI itself, it's iTerm. And while it's imperfect, what I get is this:

I can open and close sessions nearly instantly and tile and window and tab them as flexibly as I want, plus it's a system I'm familiar with in terms of shortcuts etc. Has my configured theme, fonts, etc all set up. Every GUI app is different, every TUI app has half of the UI already incredibly familiar to me, it's not "just text", it's iTerm.

That also means they all are the same - I run Codex and Claude and pi side by side, and i switch between them with no overhead and minimal mental model shift. Sure, different harness does suck but that's the same issue with GUI just with an additional new layer to learn.

Smaller thing is because it's all text, there's no limits on my ability to copy things out. And it's a really fast text renderer that can render tens of thousands of rows efficiently. Many GUIs have various dialogs, unselectable areas, virtualization, or just slow past a point. I trust my terminal scales.

Just a few reasons.