JPII fans in the US like Weigel actually have done quite a bit to alienate milennials from the Catholic Church.  I can think of three trends off the top of my head.

1.  US Catholicism has become overly politicized and too cosy with the GOP.  People of all political stripes should feel comfortable in the Catholic Church and their prudential judgments on voting shouldn't be questioned.
 
2.  There is a hypocrisy based on wealth and power.  Rich people get access and special favors, which is contrary to the Gospels.  Many milennials witnessed this in parochial schools.  The rich students were never disciplined.

3.  JPII created a culture among the Catholic laity that suggested that bullying and tattling on other Catholics are okay and that it was okay to turn a parish into an elite country club where people like gays, single moms, singles in general, etc. aren't welcome.