> Ideally you do want them to be the same, so that the skill of using one reinforces the skill of using the other,
I've used several dozen shells, script languages, and programming languages - and have needed to do within the context of a single job. What's one more? For an interactive shell I prioritize writeability, and for scripts I prioritize readability and maintainability. These are often at odds - not just in what I write, but in the syntax itself - and by making my shell and script the same, I make middling compromises resulting in a jack of all trades that is a master of none.
I disagree that this is "ideal".
> and you can begin to shape scripts out of your shell history.
It's been my experience that this is quite doable even when the scripting language has different syntax than your shell. Oh, sure, it's not as simple as Copy+Paste - but it's never that simple. Even simple shell scripts inevitably end up needing error checking, sanity checks, error messages, ...