the only men there, they won't be able to be "invisible," so they stay away. As an introvert myself, I can tell you that attending an event like this as a paying customer and trying to figure out which of the 200 women to approach would be absolutely nerve-wrecking.
This creates a bit of a catch-22 where introverted men stay away because of the dynamics of the typical meet-market, but, if more men actually came, they'd feel more comfortable.
I know some event organizers are doing some reverse marketing --- i.e.: instead of having a "first 20 women get in free" promotion like many clubs do, they're offering those types of deals to men --- to make the numbers more even. But, since there really isn't much you can to do change the overall dynamic, this seems like a band-aid on a broken leg.
Perhaps, like the club scene, relationship panels and other meet-markets serve a useful purpose, but just aren't the best place to actually meet people you might be interested in. And, as long as there are myriad ways to meet people organically --- grocery stores, professional organizations, Megabus lines, Ebony.com comments' sections, etc --- why attempt to fix a "problem" that isn't really worth fixing?