Why should the media care? Most mma media is U.S. based, so it was on at ridiculous hours. Also, it's not like Rizin has a bunch of relevant fights/fighters. It's unknowns and over the hill guys, hardly worth the coverage. The media also ignores ONE outside of paid content, Road FC, ACB, BAMMA, Pancrase, Shooto, M1, etc. etc.
Also, it's not like Rizin really cares about the western/English speaking audience. Just like in the Pride days, they are Japan focused. Pride only startyed thinking about their U.S. fans after they started losing money as a last ditch effort to stay afloat.