WHAT hairy havoc have Jennifer Lopez, Beyonce Knowles, et al wreaked upon the world of up-and-coming black and Latina starlets? WHEN did Christina Milian, brunette teen songstress and star of last year’s Love Don’t Cost a Thing, have her handlers reconstruct her image and give her a post-Beyonce blonde re-do? WHY did no one realize that “Dip it Low” is a strong enough pop single on its own merits that its vocalist did not need this egregious white-person-accessibility reinvention? WHEN did we forget about that scene at the beginning of Spike Lee’s Malcolm X where the young leader of the Black Power movement becomes embarrassed by his usage of hair-straightening products? WHY has Angela Davis never fronted a pop group?