"...why many millennials are walking away from the RCC."

According to Pew Researchers, among others, millennials are walking away from all churches, Hn Tn, whether clerics "dress up" (in cassocks) or "dress down" (in shirts and ties). Clerics of nearly all Protestant churches, for example, don't wear cassocks, yet American Protestantism -- which includes millions of millennials -- has dropped from 65% of the US population (in the 1960's) to 46% today. Needless to say, some millennials leave American Christianity (for good or temporarily) for a variety of reasons, but certainly not over liturgical vestments. Some have little need to deceive themselves over vestment lengths or over a new liturgical design, especially while pretending to sentiments and internal religious beliefs that they do not genuinely feel.