You're replying to someone that says POSIX shells are holding people back, not that the terminal is a bad idea, there are many alternative shells which offer benefits over POSIX shells. fish-shell has everything you want from an interactive shell included, xonsh is a mix Python shell, nushell and elvish are adding types and other things to shell.
The VT protocols that all shells have to confirm with are pretty dated and I'd love to throw them off the roof for something less stateful and with multiple font sizes but there's no arguing that text based interfaces are good.