With the closed beta, $msgtags returns the full string of tags, leaving the scripter to parse, unescape and grab the value for a specific tag. I purpose extending $msgtags:
If no parameter is specified, the full received msgtag entry should be returned (as it does now)
If a parameter is specified, it should be assumed as a tag name for which that tag's value should be returned
echo -a $msgtags
;; @color=;display-name=SReject;subscriber=0;turbo=0;user-type=
echo -a $msgtags(display-name)
;; SReject
echo -a $msgtags(subscriber)
;; 0
echo -a $msgtags(turbo)
;; 0