Hmm. I can understand why scribunto is targeted at template editors - although the argument that the end user is *not* the person using the template is kind of like saying the end-user of a car isn't the driver.
I'd say it's more like saying that the end-user of a crank pin [1] isn't the driver of the car it's in. Which is pretty much true, because the driver will neither think about, nor probably ever see, the crank pin. Yes, they're technically using it, but it's so far below the analytical level they're using to drive that it's not worth considering.
In a similar manner, while Lua (and PHP, and JavaScript, and so on) is being used to generate the page they're viewing, the user has no interest in that, most of the time.
Of course, if we can convince people to learn more about Lua through this very simple editing interface, then that's an awesome win and will lead to a more computer-literate user base. Then maybe we can have this chat again in a different context :)
[1] http://en.wikipedia.org/wiki/Crank_pin