You’re right.
Pearl Harbor in 1966 was the same distance timewise as 9/11 is this year. Anyone under 25 has no living memory of 9/11, just like most of us had no living memory of Pearl Harbor in 1966.
Furthermore, there is a revisionist history demon that comes with the advance of time. I bet in 1966 there were a bunch of hippies saying that we deserved Pearl Harbor because we were leaving Japan no options in halting oil shipments, etc. Indeed, per https://glencoe.mheducation.com/sites/0012122005/student_view0/chapter25/where_historians_disagree.html, Roberta Wohlstetter in Pearl Harbor: Warning and Decision (1962), undertook to answer the question of whether the administration knew of the attack in advance. On a parallel timeline basis, this is 2021.
What is different now vs then is the radicalization of the opposition. While some hippies probably believed Roosevelt stood and watched as our men died on Dec 7, 1941, they were likely not fans of Japan. Today, there is a demolition derby of leftists who think it’s racist to talk about the hijackers joined by nutjobs who think 9/11 was an inside job or the work of Israel etc. That radicalization has whittled down the impact of culture to reinforce the horrors and learnings of 9/11. Finally, as you note, the MSM is anti-9/11 for 51 out of 52 weeks of the year.
What needs to be done is for folks to talk to the Millennials and GenZers about that day, and not rely on the MSM or culture to do our job.