I think it's a 2 fold issue......and I speak from experience because I've never officially competed.
a) Lots of people including myself are either intimidated, confused or even insulted at all of the different rules and different organizations. Simplify it so anyone with any set up can participate. Just break it into a target(long stab, scoped sights, v-bars, etc) and hunter(short stab, no lens but allow sliders like hunters use, and no limit on speed, weight, or arrow/fletching). If I have to get different arrows, slow my bow, change my sight to be in a hunter class I'm simply not interested.
b) Create different flight/handicaps so the 30th place guy has a chance to place #1 in maybe a "C" flight. Not sure if they do it or not but it would maybe make others feel more comfortable if while explaining it you let them know they actually have a chance at a good finish.