Why do Japanese songs seldom rhyme?

As a cohesive language, Japanese can only use a clear and complicated cohesive suffix to express meaning, that is, Japanese must express meaning as strictly as a computer program, which seriously limits rhyme. On the contrary, Chinese, as an analytical language, and English, as a inflectional language, can still be understood by changing the word order or slightly unreasonable expression, so as to achieve the purpose of rhyme. Furthermore, I remember that Japanese seems to be the second language with the least vowels in the world, aiueo. There is really nothing that constitutes the diversity and beauty of rhyme, and it is not needed. But in rap, it still rhymes. Generally, the last two vowels in a sentence are bet (ignoring the consonants between them), and sometimes even the three vowels are bet. This is because rap is fast, and the frequency of rhyming is consistent with the length of the sentence.