I don’t pretend to know why the wife’s blessing of the husband didn’t appear. I gather it’s a new custom that began in the twentieth century, and that before that it was just assumed that women didn’t say Birkat Hamazon, at least not in Hebrew.Hebrewbooks.org has recently added a bencher, Birkat Hamazon (Amsterdam, 5483 [1722-23]), to its database. It’s downloadable here. (You can expand the image of the cover page by clicking on it.)It is a bencher (it calls itself dos benshen) because it includes Birkat Hamazon, many other berakhot, Sabbath zemirot, and a Haggadah, but none of the actual prayer services. At a quick glance, it has several points of interest. First, the cover page (above) contains what we can recognize as modern advertising. The cover pages of most Hebrew religious books talk about how great the author is and about all the commentaries that are included. This one says, “We have newly printed the bensher with many more berakhot, laws, and songs…” The “new and improved” aspect gives it a modern feel.Another interesting thing. Most versions of Birkat Hamazon have the phrase “kemo shenitbarekhu avoteynu Avraham Yitzhak veYaakov bakol mikol kol”--as our fathers Abraham, Isaac, and Jacob were blessed with everything (bakol) from everything (mikol) everything (kol). This drives home the point that they were fairly comprehensively blessed. In this version, the “all”s are distributed among the fathers: “kemo shenitbarekhu avoteynu Avraham bakol Yitzhak mikol veYaakov kol.” The Yiddish notes explain that of Abraham it is written “bakol,” of Isaac “mikol,” and of Jacob “kol.” Seligmann Baer's notes in Seder Avodat Yisrael get more specific, citing Bereshit Rabba (although I needed a concordance for chapters and verses--unusual for Baer). Abraham: "Abraham was old, getting on in years, and the Lord blessed Abraham with everything [bakol]" (Genesis 24:1); Isaac: "And I ate from all of it [mikol]" (Genesis 27:33) (although in this context Isaac doesn't sound like he's feeling particularly blessed); Jacob: "Since God has been gracious to me and since I have everything [kol]" (Genesis 33:11).
And the one that takes us back to our earlier point about my assumption that there was an assumption that women didn’t read Birkat Hamazon in Hebrew. Ignore the highlighting at the top; the part of interest is on the bottom line.The final words on the page are "ve'al beritecha shehatamta bivsarenu"--and on the covenant that you have sealed in our flesh. Before these words is the instruction that women don't say this. I haven't seen this elsewhere. It does seem to assume that women say Birkat Hamazon in Hebrew.