Thanks for taking the time to explain the details.

If we were to start with a clean slate, could we come up with something natural while still having a clean design with respect to commands? Would it be worth it?

The fact that those details haven't sunk in after more than a decade points to an opportunity for a better design, I think. For example, I can pick up Go, Java, Perl, PHP, JS, Nim, etc and memorize the if-statement details in about 5 minutes. Whether or not anyone would use such a shell, I don't know.