I agree, however it won't be 'his' script that screws up, but the many scripts written with the old event in mind. mIRC seems to have a hard-coded list of the number of parameters that each event takes, this is why we can have 'on *:blah:whatever:/this is the alias' and mIRC knows where to begin execution of the script. Changing how many parameters on NICK takes would break every script that uses the event.

This could also cause headaches for people that want to catch the on-nick event for something totally unrelated to a channel, for example:

Code:
on *:nick:*:{ echo -s In case you didnt notice, $nick is now known as $newnick }


How many times would this trigger?