It's a good idea Easy enough to script a workable alternative until (if) it gets added. Replace -e with -u99999999 to ignore them for 3+ years. Ignores set with -u<N> are not (usually) written to file and are unset when mirc exits.
Code:
alias ignore {
if -*e* iswm $1 && -*u* !iswm $1 { $+(!,$iif(!$show,.),ignore $1,u99999999) $2- }
else $+(!,$iif(!$show,.),ignore) $1-
}