Mazal Tov, I especially appreciate your citation of the Ben Ish Hai.
I personally had understood the value of dine mamonot for sharpening the intellect differently. Unlike most areas of halacha, which deal with material objects and concrete activities, the phenomena dealt with in dinei mamonot are by definition abstract entities - ownership, partnership, kinyan, etc. - and therefore our analysis of these subjects occurs on a more transcendent plane of thought.
This would also explain why dinei tuma v'tahora are considered the entryway to ruah haqodesh - the abstraction they involve is even greater, since the constructs of purity and impurity operate independently of any material base whatsoever, they are purely theoretical.
Interesting view. Although, upon further examination, I realized that most of Torah deals in ideas that are purely theoretical and you cannot physically see any differences if not for the Torah's specified guidelines. For example, just as ownership is not necessarily a physical trait but is a "legal right", so too the difference between produce which belongs to the grower and produce which belongs to the poor/Levites/Kohanim is not physically discernible, the same is true in regard to the difference between a day that happens to be Shabbos or Yom Tov in contrast to a day which is a normal weekday, or the difference between a married or unmarried woman (although in these last two differences, the difference is sometimes superficially manifested in a way that one can easily tell the different, i.e. on Shabbos people wear Shabbos clothes and married women cover their hair while single women do not), the difference between an animal that is consecrated as one Korban over another type of Korban, the difference between something which is ritually pure or impure, etc... I just brought examples from every Order of the Talmud. Rather, if anything, one can say a pshat that is the complete opposite of yours. All other facets of Torah learning deal with theoretical ideas, but those dealing with civil laws seemingly deal with more practical laws (so for example, every argument in Nezikin would seem to be an argument in the reality of the world), therefore, one would think that the learning of civil laws under the Torah's guidelines would not have the same supernatural effect that learning any other topic in the Torah would have. Therefore, the Mishnah had to tell us specifically that even the laws of money have this supernatural effect on one who learns it just like learning any area of Torah. See Einei Shmuel to Bava Basra 175n who says this pshat.