Making information more accessible and approachable never harms society in the long run.

Your view is just a snobbish and rigid one, Sagan made science topics interesting for more people, from those people very likely many got inspired enough to pursue deeper science training.

Dumbing down is necessary to make it interesting for people who feel it's unapproachable, it breaks a barrier, I have no idea how you look at this and think "this is harming society"...