Couple of notes:
1) That previous thread is actually only 9 months old (you probably looked at the original poster's 'reged' date by mistake), so there hasn't been a new version of mIRC since that thread took place (well OK, 6.16 was released two days later - but it was hardly gonna be added in that time). Which means recursion have been implemented already and we just don't know it yet.
2) If by 'never answered' you mean Khaled didn't respond personally, then about 99.999% of the feature suggestions aren't answered. Typically, the 'answer' comes in the form of whether the feature is implemented in the next version of mIRC (in which case, see point 1 again).
As for the 'causes more problems than it solves', well that's simply down to the fact that mIRC scripting is generally designed to be as newbie-friendly as possible, whereas a 'proper' programming langauge is more concerned with providing power and efficiency with the cleanest code possible. Even if that weren't the case, by already allowing a command to be called within an alias of the same name and having it behave as the built-in command (eg. alias msg msg $$1- $+ !!!!!) it'd be impossible (read: stupid) to change that behaviour now to act as recursion. That is, unless the alias switch idea or something else along those lines is used, in which case all those problems go away and nobody can complain one bit.
