The way I like to deal with allowing values to be quickly modified in a script is to put lines like this at the top:

alias -l { return MyGoatBot }
alias -l bot.owner { return MeMyselfI }

on *:PART:#:{ if (($me == $ && ($nick == $bot.owner)) { part $chan wait for me! } }

In any case, I think the biggest problem with adding subroutines is that there are already ways to deal with the problems that it solves. I don't think the benefits are really worthwhile compared to the added complexity required.