In response to your question, quoting your words, about "the problem of Kisui HaRosh, and what this custom is based upon:

It is an explicit law[20] - and not only a custom - of the Torah that a (married) woman is to cover her hair, Kisui HaRosh. Moreover, from the great reward received for performing this law one can apprehend that there is great import to fulfilling this law....

As the Zohar states[21] in Parshas Naso, [quoted in Mishnah Brurah, Laws of Krias Shema, Chapter 75) and I choose to quote only the blessings mentioned there, omitting the negative aspects resulting from failure to comply with this law: "Her children will enjoy increased stature over other children; moreover, her husband shall be blessed with all blessings, blessings of above and blessings of below, with wealth, with children and grandchildren, etc."

I would also add to the above, that it boggles the mind that this should be a "problem" for anyone who has a spark of faith in their heart and desires that their married life be truly fortunate and blessed - these blessings and good fortune extending to the husband, wife and the children that G-d will bless them with.

Can there be any comparison whatsoever of the unpleasantness (even if you wish to say that there is unpleasantness) that exists in Kisui HaRosh in comparison to G-d's blessings, the blessings of He who formed man and created and conducts the world?! Such an attitude is exceedingly irreverent, even if there were to be but a scintilla of assurance about this requirement, and surely when this matter is stated explicitly.

It is self-understood that I am aware of the objection to the above, to the effect that there are many who do not observe this law. But this question already exists for thousands of years, for "you are a minority among the nations," and how is it that "our laws differ from all other nations." And unfortunately, within the Jewish people there are still to be found individuals who for the time being publicly desecrate the Shabbos and even intermarry, Heaven forfend.

Surely this does not at all affect in the very least, G-d forbid, the vital aspects of our Torah, the Torah of Life and its Mitzvos concerning which Scripture states, "You shall live by them," just as the making of the Golden Calf in its time (close to the time of receiving the Torah) did not diminish one iota from the importance of the Ten Commandments, and subsequently the entire Torah and all its commandments up to the present day.

Finding ourselves just several days before Purim - objections such as the above [that "our laws differ from all other nations," etc.] was the complaint of Haman, whose conclusion was not only the spiritual destruction of the Jewish people, but "to annihilate all the Jewish people, from young to old, children and women."

For the existence of the Jewish people in all places is exclusively through performance of the Torah and its Mitzvos, that were given by the One G-d to the "one nation on earth."

Excerpt from Igros Kodesh, Vol. XXIII, pp. 345-346

   

Notes:

20. (Back to text) Shulchan Aruch, Orach Chayim Ch. 75.

21. (Back to text) III, 126a.