Making your own engine is worthwhile learning experience. The same as trying to recreate any of the foundational tools that you use. Might not be the fastest or best way to make a game but a good way to make yourself a better developer.
Good points about advantages of TUI. I think the keyboard focus and speed is what often sells me on them. There’s no reason a good GUI couldn’t have those but the moment your user has access to mouse you get lazy on the keyboard part and much was said already about big GUI frameworks/ecosystems and their impact on performance.
I’m switching to it slowly. I used fish on linux and powershell on windows. I want to be able to use the same shell on both systems and prefer not to rely on microsoft. I feel that data based shells like powershell and nu are the future :)