"Again" - New Pronunciation, Old Habits?

The itsy bitsy spider went up the water spout.

Down came the rain and washed the spider out.

Up came the sun and dried up all the rain,

And the itsy bitsy spider went up the spout again.

This nursery rhyme, sung all the time in schools and daycares when I was really young, was what introduced a generation of American children to language change. By first grade, everyone knew "Well, see, 'again' used to rhyme with 'rain', but it doesn't anymore..." But the thing is, I'm still seeing some poets use the word as if the second syllable had [ej]* as its vowel. For example, take these lyrics from "Would You Love A Monsterman" by Lordi, written in 2002.

(Yeah) I would slay,

(Yeah) I would maim,

(Yeah) I would vanish in thin air

And reappear again.

And the singer doesn't adjust "again" to rhyme. (Just as my daycare-mates did, which greatly annoyed me.) So, not only did the writer know that the words didn't rhyme, the singer didn't make an effort to change the pronunciation.  Lordi does have a history of using slant rhyme in their songs ("Hell's already here, and we are living tonight - beast loose in paradise..."), but this is nowhere near close enough to be considered a slant rhyme. No shared vowel sounds, no shared consonants. So, why is this not as remarkable as it should be?

See, writers know a lot about how humans hear, and think about, words. When a non-rhyme using "again" is heard/read, something happens to our immediate perception: The "It used to rhyme, the writer's not being lazy. This is just how it was back in the day," mantra is so firmly engrained into many of our minds, that we will automatically forgive the writer. Even when we know the work is modern, it's sometimes impossible to avoid thinking about it this knee-jerk way.

Now, I'm not saying that everyone should lazy and just stop trying to rhyme altogether...but we've gotta admit, we've got some privilege and wiggle room with the word "again".

*I originally wrote the completely wrong IPA symbol there. Not just wrong, but really wrong. I swear I'm not clueless, just very, very tired.