SJSinNY has really given voice to my own feelings in this matter. If a Rav who was my poseik issued a takana such as that, and we were required to wear ugly head coverings, I would be concerned that THIS would prove to be untzniusdig, because it would call SO much more attention to the women thusly attired, probably cause a tremendous chilul Ha-Shem as the non-religious Jews around us, not to mention non-Jews talked about how Judaism is a religion that uglifies its women. There is a difference between being modest in dress and demeanor, and being frumpy and dowdy. Ha-Shem created a world of beauty to be appreciated. If someone chooses to deify that beauty and worship trees, do we cover up the trees?
As to the fashion issue – I would point out that the chassidic garb of today that we hold to be so proper, is very much the clothing of the non-Jews of Europe in years past. If it was proper to copy their clothing and adopt it then, as long as a particular fashion statement is not revealing of erva (such as a woman’s bosom) or TOO tight, then it behooves people to stop being so judgmental of women who want to look stylish. Should girls go out on dates looking dowdy also? No, we WANT them to be attractive, and we want them to ATTRACT their husbands, because otherwise there will be no continuity of the Jewish nation. when a woman is continuously told she should not look attractive in public, what makes you think she has any experience in making herself look attractive in private, either? And furthermore, considering the HUGE numbers of women who are in the workforce SUPPORTING THEIR HUSBANDS, how successful do you think they would be if they dressed in a non-professional and unpresentable manner? For that matter, how successful are MEN who dress in an unpresentable manner?