[this_is_eline]

I believe that this is partially because default shells (mostly bash) are not 'really' beginner friendly, and you usually need to spend some time configuring them to be comfortable working with them. That said, i use fish shell so what do I know :)

[tjpnz]

These companies are not even trying to re-imagine the shell, just the terminal you use to interact with it.

[this_is_eline]

They are trying tho? Warp terminal has experimental ai command search that allows you to translate natural language to bash (shell) commands. That means that you could use your terminal without ever learning how to use the shell, effectively replacing not just your terminal but your shell too.

Terminal is just the program that shows text. New terminal emulators (not all new terminal emulators, but the ones mentioned in comments, the ones op asked about mostly) are way more than just programs showing text, they are also replacing/re-imagining the shell, or re-imagining the way you interact with the shell; thay are wrappers around the shell (and more).