I believe this has been suggested numerous times. Most of the regulars here will point out (and rightfully so) the fact that much of the scripting language has no meaning in any environment other than an irc client. For example what would /nick or on text do in an application?
I can see why this suggestion is indeed popular. mIRC scrpt is quite easy to learn and can seem very powerfull (when used within its context) but I must say that for applications perhaps a platform based api (such as Win32) would be alot better.
As for the non GUI version I think this would require khaled to maintain 2 seperate versions of mIRC wich could detract from (or at best delay) future updates to the client itself.