I think what puts off a lot of boomers to rap are two things: a lack of a melody in the lyrics and unfamiliarity with samples music, and irreverent lyrics. When my parents complained about rap music in the 90s it was not about the social commentary aspect, it was specifically about lyrics about women and glorification of gang violence. Which to be honest listening to a lot of these songs again as an adult comes off as highly cringe usually. Ice cube’s “good day” for example did not age well from a lyricism standpoint, feels so juvenile like it was written by a horny teenager when you actually listen to what he says. Even Kendrick has some dumb lyrics like that.