The whole point of these projects is to evolve the shell, go beyond the current bash standard to make the work with the shell more fun and more productive. Unix

The whole point of these projects is to evolve the shell, go beyond the current bash standard to make the work with the shell more fun and more productive. Unix may seem to have limited default interfaces, but this was by design - the idea was, the programmer/user knows much better what he needs so let him build it. The system's role was shaped to provide robust universal mechanisms. Also, the current standard shell is very limited when compared to even existing unix interfaces. For example, the kernel provides select/poll system calls but standard shell has no facility to use them, so simultaneous processing of two or more data streams without blocking is not currently possible. A new shell could finally provide them.