I think the same case can be made for JavaScript. With JavaScript, you are in a familiar environment (the browser) and get to do cool stuff immediately. The distance between knowing no JavaScript and making something appreciable is very small, so you get up and running rather quickly.

I also found the JavaScript model--no classes, functions for scope and very lightweight objects very simple and easy to understand. JavaScript is a very small and mostly elegant language, which I think makes it simpler to pick up.

It has its warts, but so does almost any other language (don't get me started on Python). Besides, a lot of the warts (e.g. no new scope in loops or statements) are only issues if you already know a C-like language; ignoring syntax, scoping that way actually makes more sense. I think its simplicity and being in the browser more than make up for its faults, especially in a didactic role.