there's several things going on here.
Catholics didn't write much of their own music (especially in the vernacular) until post-1962.
I'm not sure at what point hymns in the vernacular were used, but they were certainly almost all Protestant.
hence, not any about the Eucharist. ("Alleluia Sing to Jesus" and "At that First Eucharist" are the only actual hymns I can think of that are Eucharist oriented that were written more than 40 years ago! Or at least the only ones in Ritual Song...) So all of the other "songs" in the hymnal have been written since then, and are either shallow in theological content if not heretical, and usually musically deficient. Which seems to be the general trend for the 40 years following Vatican II.
Further back then that, however, we have all of the Latin Gregorian chant. Think "Pange Lingua," or "Adoro te Devote."
Of course there are the English translations of those, but really, that doesn't leave me with many options.
well, even if that doesn't solve my irritations about why there are so few good communion songs, at least I understand why a little bit more. Now I don't have to keep wondering, "why are there no Eucharistic HYMNS!?"
there's a couple...(they're also mostly just not in my hymnal! grr!)