Why?
I’d be happy to get into the details. You

With God’s help, 1 Adar I 5782

To Elchanan Rhein – greetings,

The content and halakhic validity of the practices in the will of Rabbi Judah the Pious have been discussed extensively in the research literature and in the writings of the halakhic decisors. See the chapter on the will in the entry “Rabbi Judah the Pious” and the sources cited and linked there, including the article by Rabbi Ari Yitzhak Shevat, “The Will of Rabbi Judah the Pious – For His Descendants or for the Entire World” (on the Da’at website), which brought evidence both ways from the section headings found in the manuscripts.

As for a haircut on Rosh Chodesh – perhaps this is part of a broader tendency to treat the beginnings of the months as festive days (which is why women had the custom not to do labor on Rosh Chodesh). The prohibition on haircuts during Chol HaMoed is one of the markers of the festive nature of the festival days, requiring one to get a haircut beforehand, and perhaps along those lines Rabbi Judah the Pious instituted this also regarding Rosh Chodesh, that one should not get a haircut on it so that people would get their haircuts before the eve of Rosh Chodesh.

With blessings, Yaron Fischl Ordner

And perhaps also during the Counting of the Omer they had the custom not to get haircuts partly because of the festive character of the days between Passover and Shavuot, since on those days too women had the custom not to do labor at the beginning of the night.

That does not depend on the section headings, since those can at most testify to what Rabbi Judah the Pious intended. But even if he intended it for the whole world, I don’t work for him.

Rabbi,
Can you elaborate?

Does this not have the force of an enactment or a custom?

And if not, then where are people going wrong in thinking that it does?

An enactment has force only if it was enacted by the Great Court. A custom exists if people actually practice it. The fact that Rabbi Judah the Pious practiced something does not make it a custom. If I practice something, that does not make it a custom that obligates you.
There are various strange approaches according to which anything written in a book from the period of the medieval authorities (Rishonim) is binding Jewish law. If that’s their view – ask them.

With God’s help, 2 Adar I 5782

A personal custom may not obligate his descendants, but it is still possible for the practice of an individual to be accepted as a custom by members of a particular community or place. Then its halakhic validity must also be discussed.

Aside from that, advice and guidance that came from one of the medieval authorities (Rishonim), especially someone known as a sage in the esoteric tradition, has some place to be adopted either as a good practice or out of prudential concern, for fear that one who ignores his instruction should be concerned that he may not succeed in what he does.

Be that as it may, whether it has binding force or not, and whether we follow his will or not – even the ordinary conversation of Torah scholars requires study, and all the more so guidance and instruction from a pious sage and kabbalist among the medieval authorities (Rishonim) require study and analysis in order to understand their source and rationale. It is Torah, and it requires learning.

With blessings, Eliam Fischl Workheimer