I have to agree with some of the other responses. At the least, we haven’t been given a good example of why a less powerful language would be better, but rather why it’s important to have easily parse-able output.
Feasibly you could even have some server based Java code generating the web page in a nice, parse-able format, just like you were using RoR or PHP - and I fail to see how using a simpler language to produce the same text output would be better.
If analysis of the code itself were being done, though - but even then, I’d think that more concise, legible code would be easier to analyze. Though I don’t see why many people would want to do that (with another language, at least). Extending a program, on the other hand, is something that people would want to do, and something that’s fairly prevalent with AJAX; but I fail to see how it’s the language’s lack of power that allows this.