JL Matters because it introduced the world to John Stewart. They showed the initiative with diversity even when their books weren’t doing it.
Looking back the show seemed to really take risks. It was a great introduction to a variety of heroes that you might not have even heard outside of reading particular books. For example learned about heroes like Vixen, Hawkgirl, another GL that wasn’t Hal and even the Martian Manhunter.
You could root for your favorite and you got a different adventure each episode. Watching that show it felt like the best thing ever growing up plus I think they had a crossover with batman beyond and static.
Justice League for me felt like great forward movement and payoff as a fan that watched the Batman and Superman shows prior. Seeing a team with characters so different and new to me. I wanted to know more about the ones I never heard of.