I think people are disappointed that churches now are moving away from traditions, and in to funky modernism. Sometimes it’s good to walk in to a church that takes you back to when life was simpler, and church was a dignified and comforting place. Rock ‘n’ roll bands, strobe lights, etc., don’t evoke positive feeling for many.
I joined my local church when I was baptized at eight years old, and have joined churches where we’ve lived after that. Now I’m not a member. I don’t think there’s anything wrong with it; if someone wants to join, that’s fine. Still, I haven’t seen anything in Scripture that says, or suggests, that people officially must become members of a church. If/when I see that, I’ll join our church. We’re as active as any members, and we strongly support it in every way.