I think we also have to consider kids as readers here. Children are still learning about language. They won't know what slant rhyme is. To them rhyming means words that end with the same sound.
I also agree about the music and voice adding to the mood. I do listen to words first. I'm a story girl. I want a story in my songs. I can't stand Bohemian Rhapsody specifically because the words make no sense. (Although I do appreciate the music with no words.) But lyrics, like poetry, may have a meaning for someone else that I can't see. Also, we associate songs with moments in our lives, giving them more meaning (depth) than they'd otherwise have. The music and the lyrics can be taken separately sometimes. Other times, like with Piano Man, they have to match the way words and images must match in a picture book.
One thing about what you said, Arona, confused me. To my ear, hawk and talk do rhyme. Rhyme is about sound, not spelling. There may be regions where these words aren't pronounced with the same sounds, but they are where I live. So, bread rhymes with red and said. Rhyming rules are sound rules. You seemed to be contradicting that in your rant, but perhaps I misunderstood.