Seth Godin talks about the scarcity shortage, i.e., how the value of something can hinge on how hard it is to come by. Well sure, if diamonds were a dime a dozen, that's probably what they'd cost.
But when it comes to your meeting, the lack of scarcity can really hurt. This happened way back when, as editor of an environmental magazine in a former life, I watched vertical shows in that segment just explode, even in some pretty niche-y areas. Then the inevitable winnowing began as more and more people were scrapping for the same finite group of attendees and exhibitors.
I agree, of course, with the respect, honesty, good judgment, and trust thing. And with killing a boring meeting rather than letting it get beat to death by the competition. But I'm not sure outsourcing necessarily would bring you an "insanely low-cost structure" (though it might in some cases) so maybe this doesn't quite hold for meetings.
What would be the differentiating factor that lets one show in a crowded field thrive, while those around it wither away? I don't know, but it can be painful to watch shows try to beat each other to death. I'd probably try to find an underserved niche within the niche, and build a new meeting around that, rather than continue to try to outshine the growing competition. Unless, of course, my event was winning!