I think emacs is a good example of a terminal program (not really command line) that made a good success out of becoming more gui and I think it shows a lot of the limitations of the terminal emulators. In a gui you easily get all the colours and not many weird duplicate keyboard shortcuts (exceptions are eg TAB vs C-i and M- vs ESC). You can have images and clicking and middle click paste and multiple fonts and some OS integration. But the interface still remains a fundamentally mutable text-based thing.

For something completely different: https://hisham.hm/userland/