Well "Web 2.0" isn't really powered by languages like Python or Ruby, it's powered by the XmlHttpRequest object made available in modern browsers by exposing it in client-side languages like Javascript and VBScript. Sure, on the server-side an interpreted language is used but there's nothing new in that, and there are
dozens if not hundreds of languages available for that task. So why add another? Like you said, languages like Python and Ruby have really raised the bar on power and simplicity, so if anything that just means there's less of a reason for a general purpose language based on mIRC scripting.
Besides that, I don't think a general purpose language based on mIRC scripting would even work. The number of fundamental changes needed to make a mIRC programming language work effectively outside of the mIRC environment would make it as different from mIRC scripting as any existing language like Perl or Python.
