For the longest time I was one of them, in spite of being probably one of the very early adopters for 'ajax' (before it even had a name and you had to jump through hoops to get data back to your wannabe page modifying script).
I sort of lost track of how fast the developments where going and then somewhere I ran into this apple II emulator in js. It completely floored me that that was possible.
Oh yeah, back when you had to use the invisible IFRAME trick.
I used to think JS was a retarded language too, before I realized that "dynamic" languages are just as powerful and often far easier to work with than "static" ones. The browser environments in which JS is usually found don't make it easy to see the merits of the language itself, and the language itself has some annoying quirks, so I can understand why people would be reluctant to like it. But more and more I find myself wishing that I could use JavaScript as a general purpose scripting language like I tend to use Perl or Python today.
You can, check out Mozilla Rhino. It's a javascript interpreter written in Java. You can use all the Java libraries through it, but I'm not sure if it'll be quite as nice for working with files etc
I'm still wondering who these people are that think JS is a "kid's" language.