The thing about Monbushō shōka ("Education Department songs") (previously) is that the government commissioned them. Everything about them embodies the top-down cultural agenda of the Meiji power structure. Even the word shōka 唱歌 was a Meiji neologism*, referring to both the songs themselves and their "correct singing" as an official subject in school, with the goal being to "cultivate the morality and mold the virtue" of the students.

And so, although the word was most likely intended to translate English "song" and "singing" in general, it quickly narrowed to refer specifically to the songs children learned in public schools, and the singing thereof**. I even found someone complaining that the term 学校唱歌, "school shōka," is redundant in the same sense that 武士の侍, "warrior samurai" would be.

Another area of high agenda visibility is the lyrical content of the songs. One example that came to my attention recently: "Yorokobi no uta", IWASA Tōichirō 岩佐東一郎's shōkafied take on the Beethoven/Schiller Ode to Joy.

晴れたる青空　ただよう雲よ
小鳥は歌えり　林に森に
心はほがらか　喜びみちて
見かわす我らの　明るき笑顔

Clear blue skies/ drifting clouds
The little birds are singing/ in the forests, in the woods
Our kokoro are merry/ full of joy
We look at each other with/ bright, smiling faces

Can you imagine a full choir belting out this crayonic idyll? It's like the mirror-universe version of Hubbel's "O thou unrippled pool of quietness" Bashō parody.

No, surely what has happened here is that Iwasa and/or his editors liked the melody and the general idea of singing about happiness, but decided to craft a new set of lyrics that would foster morals and good cheer rather than frenzied, cosmic ecstasy.

Non-government poets of the time found this sort of insipid preachiness (and stilted language) so distasteful that they actually founded a private magazine to publish their own poems and songs for children (dōyō 童謡). Thus was born the Akai tori ("Red bird") movement, named after the magazine itself. To be fair, many of the Akai tori dōyō come off as pretty insipid today as well, but they were at least written in language that children could understand.

Bonus Ode to Joy factoid: Although its first performances in Japan took place in P.O.W. camps during WWI, it wasn't until the postwar period that Beethoven's 9th became the end-of-year program fixture that it is in Japan today. Problem: Everyone wants to sing along, but not everyone can read German. Solution: Throw together a bunch of nonsense ("Get out of the bath, sleep to a poem, moonlit powder-build...") which will, when pronounced aloud, give you a katakana-German rendition of the lyrics. I seriously doubt that anyone ever considered this more than a lark, but it did work for Yan-san.