Haven't you listened to any of the J-pop lyrics? They are so bad, their existence itself is beyond joke.
I totally agree, and their aesthetic has never quite grown out of American 80's music. They are mostly cheesy party anthems and corny ballads.
And just like how all the Japanese girls look, they all sound impressively similar.
I can't stand Japanese music because I'm a musician, and when ever I hear them, I can't stop analyzing the structures and melodies.
It seems that almost all major key music has this "Omatsuri" or "Bon-Odori" lines, and minor key music carries the trait of "Enka."