I've also met a lot of people who seemed to know about J2O but didn't feel like visiting it much for whatever reason. I doubt the problem is in the knowledge about J2O's existence.

I can understand the sentiment though. I played Q3A and UT casually for some time, but never felt like looking at the sites because I didn't have the need to get involved much. Just joining a random server every now and then was enough fun for me and I saw no need to get involved with the "community", whatever that was. I can imagine those people not visiting J2O feel the same.