I'm not sure that a cleanup is absolutely neccessary since a yukata is by definition (and mostly by appearance) a light summer kimono. I can see where it would get clunky where every open yukata takes all four tags though.
That's true for every combo tag, and is a limitation of the system. I guess a better argument is why we don't use open_kimono for open_yukatas. The alternative is the case where everything is aliased properly, and every open_yukata gets tagged with all four tags.