Woodstock Co-Creator Tells Purists to Quit Bitching About Modern Lineup

Jay-Z, Chance the Rapper and Common are gonna attract a new generation to Woodstock 50 and anyone who's not down with that better get the hell over it ... STAT!!!

Michael Lang -- the co-creator of Woodstock's 50th anniversary festival -- tells TMZ ... he heard about the backlash the festival has received in response to the lineup it released last week. Fans bitched it's too pop and modern, with artists like Miley Cyrus, Imagine Dragons and Halsey.

The backlash was intense. One person tweeted, "The Woodstock 50 lineup looks like it was curated by someone who's only exposure to music has been through the Grammy's 'Best Rock Performance' category between 2010-2013."

But, check out the video ... Michael makes it crystal clear the lineup is an homage to the original 1969 festival ... where more than 400,000 spectators gathered in the Catskill Mountains united by their love for great music and disdain for the Vietnam War.

Michael says he's hoping to get a younger audience engaged in social discourse -- just like his generation once did -- and in the process, introduce Woodstock to a whole new generation.

So, while there will be familiar acts for the veterans -- like Santana and Dead & Company -- Michael's adamant Woodstock will benefit from an eclectic lineup.