“I wish people would stop being such straight arrows ONE day of the year”
Purim is not a day off from Yiddishkeit and keeping the Torah even if you wish it was.
There is a difference between following halacha and being a straight arrow. I think you misunderstood Oomis’ point.
As for loud clothing – in Asia, loud colors are very normal and as far as I remember are allowed. However, there were other things that were restricted in Asia (I think that the back of the neck was considered immodest by Asian society so Jewish women covered it too).