At age 6, my DD had friends who were swooning for Justin Bieber. DD was open in her contempt for him and his music. It didn't cause any problems that we saw.

These kids DID bond frequently over movies and Disney/Nick TV shows (their imaginary play often meant taking on TV roles and playing them out in absurd ways), so that was a major source of social currency. Also, contrary to what someone said above, they were already Minecrafting, plus playing other cooperative video games like Just Dance and Lego titles. So those were all pop-culture resources that helped DD bridge the gap to other kids.

As far as music, the most important thing was that there were age-appropriate instruments available for the kids to goof around on (small drum kit, keyboards, recorder, etc.), plus some tolerant adults.