I'm sure someone will completely flame me for the comment but the practice appears innocuous to me.
Not a flame, but while the business practice of obtaining comps in exchange for a guaranteed number of bookings may be completely justified, the lack of transparency combined with the guilt, coercion, and manipulation the society uses to obtain such perks is not.
Here's a better idea. Instead of using its leverage to obtain kickbacks for itself and its "special full time service" members, why doesn't the society use it to actually negotiate better-than-market rates for its rank-and-file members, many of whom already are straining their budgets to attend given that they've decided to follow its advice on higher education and career choices.